FIM Portal Groups - Change from criteria based to manual

Hi,

I have groups in FIM portal that are criteria-based.

I need to change those groups to manual in order to add/remove users from them via my code with RMGroup resourceType.

I can´t use xpath filters anymore because it will be quite complex and FIM doesn't accept it.

I tried to, in code, remove the filter, set an empty filter, set MembershipLocked to false, ... every thing

I allways get the error "Policy prohibits the request from completing", so I still can´t add/remove users to the groups.

If I change the group from criteria-based to manual in the UI, it works but the code is calling the FIM webservices using the same credentials  I use to access the portal.

How can I do it programmatically?

Help is really appreciated,

Many thanks,

DevDiver