Citavi's Word Add-In cannot be run if the following option in Word's Trust Center is enabled:
Disable all Application Add-ins (may impair functionality)
Solution
- Open a Word document.
- Click File > Options.
- Switch to Trust Center.
- Click Trust Center Settings.
- Switch to Add-ins.
- Check if the option Disable all Application Add-ins (may impair functionality) is enabled. If it is, clear the checkbox.