Br2theian

So I just replaced my05 passenger door and the donor came from a my01 basically had to swap over everything, I got the door cylinder back on with that annoying "u" clip but it was the last thing I did. I heard it completely click into place but when I went back to look at it, it fell out and it wasn't there anymore. Anyone know a better way of doing this or some tips of getting another one on there? It took me a while to do that now I have to do it again