DES2000 User Extensibility problem?

Needing a way to specify tests for modules in a neat way in the repository, i've created 2 new objecttypes in DES2000 using the User Extensibility option.
One of the objects namely "Test" is an elementtype which basically describes what kind of test one would apply for a module to test if it is working correctly; instances of this "Test" could be eg. datecheck or integrity or whatever.
The other object called "Test of Module" is an association type beeing a "many X many" between "Test" and "module", and allowing for relevant attributes here as well. In these two new objects i've also included new properties and text-types relevant for theese, like "Expected outcome" and so on.
When theese are posted and DDL created the "Test" will show up in the RON at the same level as table, modules etc. and "Test of module" will be subordinate to "Test" showing up only when a "Test" is assigned one or more modules.
Creating "Test"-instances works fine, and assigning these to modules also. But I get an:
RME-00222 Failed to dispatch operation to repository when trying to delete a "Test"-element (not assigned a module), but have no problems deleting the association ("Test of Module"). Anyone got a solution here?
BTW: any comments on implementing the ability to describe moduletest in the repository like this?
Best Regards

-- 
Oliver Felix Fox
Copenhagen, Denmark. 
Dansk Data Elektronik A/S
E-mail: off_at_image.dk / off_at_dde.dk