Don't know if i'm just being a control freak this early on, but of late trying to put my 6wk old down in his cot is a battle.
I'd rock him to sleep in my arms first, make sure he's properly sleeping then put him down in his cot; after about 15 mins he's screaming like his life depended on it! He will quiet down very soon after i pick him up. Patting him while he's in the cot doesn't help. Turning on the vibrating thing in the cot doesn't help. So far he likes our bed if we're lying next to him, or better still if we just held him constantly... what's going on, he's only 6wks old..!