Error in Adapter FrameWork

Dear All,

While doinf File to File scenerio, i m getting following error in Mesage Monitoring in Runtime Workbench "Transmitting the message to endpoint http://trexserver:8000/sap/xi/engine?type=entry using connection AFW failed, due to: Received HTTP response code 403.."

Plz tell me what this error is all about and how this can be solved.

Reg,

nishu