Debugging of a user-exit for /SAPAPO/CCR on the APO side

Hi,

Kindly help me with the steps to debug a user exit (EXIT_/SAPAPO/SAPLCIF_SLS_001 in my case), while pushing a sales order from R/3 to the APO system. I tried putting a breakpoint within the FM as well as the include(both session and external), but it did not stop.

Thanks in advance :-)