Liftgate closing/locking issues?

I have a 2004 LS 2WD. Recently I noticed the remote unlocking stopped operating. With the doors closed, the interior lights don't fade out and I have to push the manual door lock twice to secure the doors. I think it has something to do with the liftgate/rear window not being recognized as closed or something (the rear gate does not lock at all unless I do it manually through the rear panel). I can't find any physical reason why it would think the liftgate is not secure (it is). Any suggestions would be appreciated.