I am using a ptlb10u projector with a vcr connected to the composite input and the keystoning feature is grayed out. It remains grayed out no matter whether I have the auto-keystoning on or off. If I use the s-video connection the keystoning becomes accessible. I have tried resetting everything to the standard factory settings and the problem remains. Is there a reason for the inaccessibility of the keystoning feature with composite video via a vcr?