Error 645

I am running Zenworks 2.7 Application launcher on a 4.11 Novel network.
For some reason, the App launcher is no londer displaying applications.
When I go into Network Admin, it says

"The Schemas for the NDS trees listed do not contain the latest
Application Launcher changes. Select the trees you would like modified
and choose the "Modify" button below to update these trees"

I choose the tree and click "modify". It then says

"Error -645. The schema on tree could not be updated"

Does anyone have a suggestion on what the problem is and how to fix this?

Thank you