TV shows purchased from iTunes - synching issue

Hello everyone.

I have an issue where TV shows I've purchased from iTunes initially synch across to my iPod so that I can view them on there, but when I do a subsequent synch the TV shows disappear from the iPod and won't go back on, despite being present and correct in iTunes on my Macbook.

Has anyone else had this issue and managed to resolve it?

Thanks,

Mike.