Thanks Walter, I have checked the interface and my prg, and i can sure every event have been implemented.But it still doesn't work.:(

So i carefully explorer the interface sqldmo's backupsink, found that it's an Iunknow Interface.Almost in every sample about implements com interface--outlook application,ado.recordset,etc...--they all use an IDispatch Interface. Is that means we can't implements an IUnKnow Interface? And there even haven't an topic about "Implement" in vfp's help!