I was having this problem with DD up until yesterday! Although it was reversed, she would scream the house down during the day but will be put to sleep in her cot wide awake at night and would go to sleep all by herself..
But what i did yesterday was i put her down she would start to grizzle (which usually turned into screaming if left for another 10 or 20 seconds) so id give her her dummy and walk out, she would spit it, grizzle, i give her her dummy again etc..eventually i realised i hadnt needed to replace her dummy for an hour and she was asleep..it worked the whole day. Today i didnt even need the dummy she settled herself and now is asleep..im hoping its a keeper!!
Ive got a thread going that i started yesterday with some tips from othe rmembers already if u would like to pop in What can I do??