Break points are not triggering in RFC from portal application

Helllo,

I am running Biller Direct application from portal, which is triggering a standard SAP RFC FM back end, am trying to debug my execution from portal, for this i put the External Break point, Session break-poiint at the beginning of this SAP RFC FM, but, its not stoppping at ll, here the user is a Web user, not dialog user.

How can i stop my execution in this SAP RFC FM to check how the structures are populated?