Re download iTunes purchases

Dear community.

some time ago I purchased a number of seasons of pbs' Word World for my kids. Now I cannot redownload them. I can find the seasons in the iTunes Store and I can find them in my "purchased" list in the iTunes Store, but when I try to download them The site states that they are not available in the US iTunes Store. As stated above, this is not true. How can I get what I paid for - my kids are eager to watch the shows and I have paid good money for the shows. I can't believe that my purchase is suddenly void ... that negates all the benefits of purchasing shows, music or movies on iTunes rather than dvd's or cd's. Any help would be much appreciated.