Diagnosis
When a rental unit is created, it is simultaneously entered in theincidental expenses collector. However, this is only possible if therental unit has not been entered in the collector up to this point.

System Response
The rental unit which you want to create has already been entered inthe incidental expenses collector, presumably due to a memory error.

Procedure
You should inform your system administrator in any case. You can repeatthe "Save" function in internal number assignment and another number isthen assigned. For external number assignment, you can only save therental unit which you have just created if the error has beencorrected.