Enhanced component asks for registration key after system copy

Dear experts,

to be able to develop with high quality data we rebuilt our CRM development system with a system copy of the production system. Now after finishing all the reworks (BDLS, SCC4, ..) we have the following problem:

Whenever we try to create a new event to an already enhanced component, the system asks for a registration key as if it wants to modify the SAP standard classes! One time we tried what happens if we enter this registration key: The systems trys to redefine its own methods in the SAP classes and therefore results in a syntax error.

Has anyone an idea what settings might sill be wrong that lead to this system behaviour?

Thanks so much

BR Matthias