A couple suggestions to go along with the above...
I put a sheet(like the ones they have in the hospital??) doubled over between lo's crib sheet and mattress, this was suggested by the health nurse, as with the plastic mattress can be really warm and both cold, which can cause waking.
I also put a shirt of mine that I have been waring that day to bed with ds, and he had my scent with him. I had then bought a lovey and slept with it for a night and now he loves it.
Just a couple things to try.
HTH