Working with generic resources in SuiteTalk

Hi all.

we were able to migrate from a legacy system to netsuite generic resources allocation using the following code

resourceallocation.allocationResource = new RecordRef { internalId = myinternalId, type = RecordType.employee, typeSpecified = true };
(basically passing them as employees).

Now, we'd like to update the generic resources' externalId using SuiteTalk:

          Employee emp = new Employee();
          emp.internalId = internalId;
          emp.externalId = externalId;
          WriteResponse response = service.update(emp);

but when we update them (passing an employee type) we got a very strange error:
"An unexpected error occurred. Error ID: jauv3mzz128u3z8kjw8pe"

Any idea?

Many thanks,
Antonio