We had several users that downgraded their Microsoft Office from 2013 back to 2010 and their XL-Connector plugin stopped working. The problem turned out to be some leftover registry entries that screwed up the correct working of the plug-in.

Please follow steps below to resolve this:

1. Go to the Settings dialog of Enabler and copy the link to your log file.

2. Open Windows Explorer and paste the copied link into the address bar. The log file will open in your default text editor.

3 Look for error messages closer to the end of the log file. The right message will contain something like “Unable to cast COM object of type ‘System.__ComObject’ to interface type …” and also “call on the COM component for the interface with IID ‘{000C03A7-0000-0000-C000-000000000046}’ failed due to the following error: …”.

4. Copy the long IID string (without braces).

5. Click Start and type ‘regedit’, then hit Enter

6. In the Registry Editor that opens find the following key:

32-bit systems:
 HKEY_CLASSES_ROOT\Interface\{IID-THAT-YOU-COPIED} 
64-bit systems:
 HKEY_CLASSES_ROOT\Interface\Wow6432Node\{IID-THAT-YOU-COPIED}

With the subkeys:

 - ProxyStubClsid - ProxyStubClsid32 - TypeLib

7. Take a look at the (Default) and Version values inside of TypeLib.

8. Now find the node below, using the (Default) value as <TypeLib ID>.

 HKEY_CLASSES_ROOT\TypeLib\ <TypeLib ID> \

9. As child of this element you will find more than one element, one of them is the Version of the first registry. If you inspect the others elements, you will find that they point to nothing.

10. Remove the others.

11. The problem is solved.

The solution has been taken from StackOverflow