CRM_STATUS_CHANGE_FOR_ACTIVITY - "Deactivate Object" is not allowed

I am trying to use this function module to mark an IBase record as inactive.

The Parameters I am passing are:

ACTIVITY_ALLOWED

CHECK_ONLY

CLIENT 100

NO_CHECK

OBJNR 47113749F3D00667E10000000A20801E

VRGNG INAS

ZEILE

SET_CHGKZ

XNOAUTO

but i am getting the following error:

Exception ACTIVITY_NOT_ALLOWED

Message ID: BS Message number: 007

Message:

"Deactivate Object" is not allowed (<Unknown Object>)

I have debugged it and I am passing in the same code that i can see in the debug session when i run IB53! but for some reason, this does not work when i call the same function module!

has anyone come across this before???

I can set the Deletion flag fine, but i have set it as inactive!