Hi,
did you call '/AIF/UTIL_ADD_MSG' inside the action ? Which message type did you chose ?
Depending on the Trace Level Details certain message types are not shown in /aif/err
It can be found in /aif/cust -> error handling -> define global features -> tracelevel -> rightclick details
Did you set the action function module parameter named success to 'N' ?
if there are no messages with type E the interface thinks that it ran successfully and setting the parameter to 'N' makes it fail regardless.
Kind Regards
David