IError when downloading a movie into my library

I am having some trouble downloading a digital copy of a movie into iturnes. I have successfully done it with several other movies so I understand the process. One movie showed that it had successfully transferred, it shows in my itunes library but doesn't play when I click on it. I tried to re-downlaod but have received an error message indicating there is no disc space. This doesn't make sense, I am saving it to itunes not a disc. Now there are 3 non working copies of the movie in my library. Any suggestion? And yes I am using the disc labeled digital copy and I have successfully typed in the redemtion code. Thank you!