Ever since she was born, DD (14mo) will only nap properly in her sling or carrier, after lots of walking or bouncing. If we try to lie her down in bed once she's fallen asleep (we co-sleep, so there's no cot), she might sleep for about 20 minutes, but then once she wakes, she's awake for good. Forget lying her down to fall asleep - that's never worked, and without a cot, she just gets up and crawls off the bed. Even our bedtime routine involves a lot of feeding, singing and bouncing, but at night she will go back to sleep if we go in and feed/bounce her again.
This was all fine when she was smaller - in fact, it was pretty good for us, as we could go out unrestricted by her nap times. But now that she's getting a bit bigger and has more or less moved to one long nap rather than two shorter ones, I'd quite like to be able to set her down so that I can get some more stuff done while she's napping! Has anyone successfully got a sling-only napper to kip on a bed?