At my wits end! Baby naps like a dream but dreadful at bedtime!

Ive started back at work and the lack of sleep is turning me into someone who I dont recognise. Id really appreciate your thoughts on this: Baby boy has 2 naps a day- draw curtains, sound machine, sleeping bag, dummy, cuddle and then i pop him into his cot with his teddy and I leave. After a few mins of babbling, he falls asleep. Bedtime is a totally different ballgame. Milk he has in his room with lights on, then nappy +pj change, massage, teeth and then the same as above. But he just starts crying as soon as he goes into his cot. I end up rocking him to sleep, and he wants rocking the many times he wakes. He obviously can do self settle as he does it 2x in the day. Where am i going wrong?