Sometimes an older Java or Flash Player installation may interfere with the Deriscope GUI part (the com addin) which handles the display of the Deriscope taskpane.
The problem is often resolved after refreshing your Java and/or Flash Player installations.
You can find here English instructions for downloading the latest Java version compatible with your operating system.
You can download here the latest Flash Player.

When Deriscope is activated for the first time, a file named deriscope.cdm is stored in your computer at one of the possible folder locations below:


After a major windows upgrade or other action, it may happen that this folder or its content gets corrupted.
The solution is to remove this file and restart Excel so that you will be asked to enter your license credentials like when you activated the license for the first time.
IMPORTANT: You must provide the exact same email and password that you used during your first activation of that code.
If you have forgotten any of these, you may recover them here

The easiest way for removing the cdm file is to go to the Deriscope ribbon and select the menu option shown below:

Alternatively you can delete the file manually by searching the above folders, as described below.
1) Open the Windows Explorer and type %programdata% inside the top row where normally the full path of the current selection is shown, as sheen below.

2) Hit the ENTER key.
3) You should now be at the location where your standard ProgramData folder is kept at your machine. You should normally see a subfolder named Deriscope, which contains your license CDM file.
4) If you see the Deriscope folder, simply remove it! You can do so, for example, by selecting that folder and hitting the DELETE key.
5) If you don't see it, the license CDM file should be located in one of the other two possible folders. Go to these folders and look for a file named Deriscope.cdm. Delete that file, if you find it!

This failure may be due to the fact that your license does not support the installed Deriscope version.
At the present time all new licenses come with a free upgrades period of one year, but you need to consult your purchase records, since it is possible that your particular license was issued with a different period.
If you have accidentally installed a new Deriscope version on a date after the end of your free upgrades period, you would need to do the following:
1) Close Excel
2) Uninstall Deriscope through the Apps section of your Windows Settings
3) Install Deriscope using the installer file that you used for the installation of your most recent properly working version. The installer file is the file that is downloaded from the Deriscope server when you click on the Download button. It carries the .exe extension and its name looks like DeriscopeInstal_1.1.7583.35107_9.1.0.exe, where the actual shown numbers indicate the respective time and version. In this example, the version is 9.1.0, from the last 3 digits.
4) Start Excel. If the problem persists, see the Remedy Effort below.
In case you have not kept a copy of the installer file, let Deriscope Support know so that we can send it to you.

List of Remedies

Often loading failures are caused by faulty installation due to a non-updated Windows environment.
Please do the following:
1) Close Excel
2) Open your task manager and browse through the running background processes. If you see an Excel process, kill it and restart Excel.
3) If the problem persists, make sure Excel is not running and uninstall Deriscope through the Apps section of your Windows Settings
4) Restart your device
5) Go to the Updates section of your Windows Settings and ensure that no important system update is pending
6) Install Deriscope. Make sure you pick up the bitness that corresponds to that of your Excel installation. The bitness of your Windows installation is irrelevant here! You can find out the bitness of your Excel by opening Excel, going to the Account tab and clicking on About Excel.
7) Start Excel

Deriscope requires that the Microsoft Visual C++ 2015 - 2019 Redistributable libraries be installed.
More precisely, the 32 bit Deriscope requires the x86 Redistributable version, while the 64 bit Deriscope requires the x64 Redistributable version.
It is ok if both of these versions are installed in your device.
Normally Deriscope installs the required library automatically during installation, but sometimes may skip this step.
You can check if any of these libraries are installed by looking up the Apps section of your Windows Settings
The x86 Redistributable version should look as below.

The x64 Redistributable version should look as below.

If the relevant library is missing, you must download it and install it from the Microsoft site as follows:
For the x86 Redistributable version use the link vc_redist.x86.exe
For the x64 Redistributable version use the link vc_redist.x64.exe
Alternatively, search online for a download site with the required library described above.

Excel may have suppressed the loading of some critical component.
Please do the following:
1) Start Excel
2) Go to the Excel Options screen. In Office 365 this is done as follows:
3) Click on File and then on Options. Then the screen appears as below.

4) Select Add-ins from the left panel. Under Active Application Add-ins, the two Deriscope Add-ins named DeriscopeGUI and DeriscopeXLL should appear, as shown below.

5) If any of these two Add-ins is missing, check if it is under the Inactive or Disabled list further below.
6) If it does, go to the Manage dropdown at the bottom and select COM Add-ins if the problem concerns the DeriscopeGUI or Excel Add-ins if the problem concerns the DeriscopeXLL.
7) Check the corresponding checkbox in order to force the reloading of the corresponding addin.
8) Restart Excel if needed.

Excel may have suppressed the loading of the Deriscope DLLs due to very strict security settings.
Please do the following:
1) Go to Excel Options as above and select the Trust Center tab from the left panel.
2) Examine the various settings to see if any of them may be responsible for blocking Deriscope.

Excel may have flagged the Deriscope addin as unsafe and "permanently" blocked its loading during startup.
Excel does so by setting a number other than 3 in the LoadBehavior of the Deriscope addin in registry.
More specifically, Excel associates with each addin a number from 0 to 3 - referred as LoadBehavior - that has the following impact on the addin's loading:

Please do the following:
1) Close Excel.
2) Type regedit in the "type here to search" input field that appears when you click on the windows icon located at the left bottom of your screen.
3) Give your consent for administrator access when a prompt appears and navigate to the folder where Excel resides. The exact location may vary, but below is a screenshot that shows the LoadBehavior location in a machine where Office 365 is installed.

4) If you see a LoadBehavior number other than 3, change it to 3 by right-clicking on the LoadBehavior label and select Modify.
5) Start Excel.

Same as above, but this time Excel has added an entry under the DisabledItems group of the Resiliency folder in registry.
Please do the following:
1) Close Excel.
2) Access the registry as above and navigate to the folder where Excel resides. The exact location may vary, but below is a screenshot that shows the location of the Excel/Resiliency/DisabledItems folder in my machine.

3) If you see any item inside the DisabledItems folder - other than the one called (Default) that is always there - simply delete it.
4) Start Excel.

Excel may be in such a bad state that only a reinstallation can bring it back to a normal functioning.
Please do the following, but make sure you have made a note of any custom-loaded Addins you may be using as you would need to reinstall them afterward.
1) Close Excel.
2) Go to the Apps section of your Windows Settings and uninstall Deriscope
3) Go to the Apps section of your Windows Settings and uninstall Excel.
4) Restart your device.
5) Install Excel.
6) Install Deriscope.
7) Start Excel.

Normally the Deriscope taskpane should react when a spreadsheet cell containing a handle name is selected, by showing the contents of the object associated with that handle name.
The taskpane also reacts when the cell contains a Key by showing the key's description.
It also reacts when the cell contains a Value that is an element of a list of context-dependent allowed values, by showing the value's description and creating a respective cell validation dropdown that contains the allowed values.
But the above standard behavior is enabled only if the taskpane's reactivity - controlled through the Tools button is set to High, as shown below:
If your reactivity is set to less than High, you may still force the taskpane to react to the currently selected cell by clicking on the Cell Info ribbon button .

From time to time the Deriscope taskpane may turn into a corrupted state.
The easiest remedy is by clicking on the Tools button and selecting the Refresh Task Pane/Clear Cache button as shown below:
If this does not work, you would need to restart Excel.

A common reason for the sudden Deriscope taskpane's disappearance is an Excel feature called AutoSave.
If AutoSave is enabled, the taskpane disappears every time the spreadsheet is autosaved.
Simply turn this feature off.
If the unstable behavior of the Deriscope taskpane persists, this will be likely the result of an "unhappy" coexistence with some other loaded Excel or COM Add-In.
It has been observed that the two COM Addins Microsoft Power Map for Excel and Microsoft Power Pivot for Excel may under circumstances interfere with the Deriscope taskpane.
The only remedy to this problem is to disable the problematic Add-Ins so that they are not loaded together with Deriscope.