1. Make sure your username and password credentials have proper permissions to modify the schema.
2. Check the Active Directory replication settings to ensure all Schema and Configuration Masters are working properly.
3. Verify that all domain controllers are online and are functioning correctly.
4. Check your application logs for errors or warnings related to schema modification.
5. Make sure your schema updates are complete and well-formed before attempting to apply them.
6. If possible, completely uninstall the application to ensure the schema remains clean and only contains the attributes and classes that are necessary.
7. Reinstall the application and review the list of schema updates that are to be applied to verify all components are accounted for.
8. If necessary, contact your technical support for assistance with resolving any issues.