M.S.
We tried the co-sleeping thing untill my daughter was about 3 months, and everything I was reading said it was a good time to transition, well she didn't think so! I had the same problem of her being fine and then throwing a fit as soon as we tried to relocate. I read something about the baby being warm and snuggly with us, and then being moved to "cold" sheets as being a shock. It made sense to me, so I would lay her on a fleece blanket and hold her or just be next to her until she went down and then "hammock" her in to the crib. It seemedo work most of the time, and now that she is used to it, she wakes a little when I set her down, but puts herself back to sleep. Good luck!