If you say "wana see a movie sometime" then its a yes or no answer youl get! So ask her in a way thats cooler.... say like "will I ever see you when Im not ill" or something more homorous then sincere!
Thats what I do anyway. Means you never get knocked back because your more testing the water than asking for a yes or no answer right away!
Just remember it doesnt have to be all on one question. Build up to it so it will be easier!
I used to be so scared to ask someone out or start chattin to them but really if you just make general chit chat then youl see the path to the main objective of a date!
Kriss