Film download problem

Hi, I purchased a film from ITunes ages ago, 2/3yrs. Sync'd it to iPad and watched it. Removed it from iPad but still on main computer. I am now trying to get it back onto iPad but only get message 'unable to download at this time,' try later' - done-retry - but have retried many times without success. Other films that I purchased at the same time have downloaded without any problems.
This is my first attempt with Mac-forums, looking forward to some expert advice.
Thanks

If the movie is on the computer, and if it shows up in iTunes under the Movies tab, then all you should have to do is to make sure you are syncing movies (i.e., check the box on the movies tab and select the movie) and then connect the iPad to sync. Shouldn't need to "download" the movie again from anywhere. Also, check to make sure you have sufficient storage left on the iPad to hold the movie.