Q: IPOD Classic 160GB Purchased Late 2012 Some Movies Purchased ITunes will not let me convert

I have an IPOD Classic 160GB Purchased in Late 2012 and I am finding that some of the movies i buy with digital copy for ITunes will not let me sync with this IPOD  some ITunes will convert for me but I have some movies that when I try to convert them to ipod format the option is greyed out will not let me make an SD version for my IPOD why is this and if Apple is no longer supporting the IPOD classic for all the movies I purchase why is it that I can still go into Target or another major retailer and still purchase this device. I paid for the IPOD Classic 160GB I paid for the movie **** it I just want what I paid for!!!!!!!!!!!!!!!!!!!!!!!!!!!!