My four month old sleeps ok at night but refuses to nap in the day. I know she needs naps because she gets cranky if she doesn't nap and also will start looking all sleepy. I've read all the things that I'm supposed to do (set the mood, look for sleep cues, consistent routine etc) but she screams when I put her in the cot. How long do I try for a nap when she refuses. I don't want to leave her screaming and don't want to be tied into her napping on me (even this doesn't always work). Any tips? I can't deal with crankiness.