Hi Pankaj,
two quick ideas:
1. Could it be that all AIF jobs failed due to a dump? This cannot be provided back to AIF and the message stay in status "in process". (check job (SM35) and ST22)
2. Did you call the method with a queue namespace and name? Is this set up in teh aif runtime configuration? Then you need to start the message processing with program /AIF/PERS_RUN_EXECUTE.
Good luck
Christoph