Problem: Custom commands and objects missing from ArcGIS applications
When you register a sample provided in the ArcObjects Developer Kit or your own custom object with one of the ArcGIS Desktop applications, the command or object provided in the DLL is not available in the ArcGIS application.
There is a 128-character limit on DLL pathnames.
Solution or Workaround
Warning: The instructions below include making changes to essential parts of your operating system. It is recommended that you backup your operating system and files, including the registry, before proceeding. Consult with a qualified computer systems professional, if necessary. Esri cannot guarantee results from incorrect modifications while following these instructions; therefore, use caution and proceed at your own risk.
1. Register the DLL.
See: How To: Register a DLL with a long pathname
2. Use the Component Category Manager Utility (\arcgis\arcexe81\bin\categories.exe) to add the objects contained in the DLL to the appropriate component categories.
Note: For more information on the Component Category Manager, refer to the help topic for this utility in the Utilities section of the ArcObjects Developer Help.