user exit not stopping

Hi All,

I am trying to test if one user exit M06B003 would be triggered before saving the Purchase Order in ME21n.

I have gone to SMOD, opened this user exit, it opened a function module by name EXIT_SAPMM06B_001.

In this function module there wasa include module ZXM06U18.

I have selected a beak point on this include.

and created a newsesion with ME21n.

when i fill up all details, and saved, it got saved and gave a PO number, it didnot stop at that user exit.

what might have went wrong. this exit is not yet used, not atleast once.