Symptom:
After upgrading Microsoft Outlook to a new version the OXtender isn't loaded anymore.
Reason:
The old Outlook Installation points to a add-in directory from which add-in should be loaded or directly to add-ins provided by 3rd party Software vendors. But the upgrade mechanism from Outlook doesn't take care about those registry settings.
Solution:
Uninstalling and reinstalling the OXtender rewrites the correct registry settings and the OXtender is loaded after Outlook start again.