Samsung

I moved some pictures in jpg format from my computer to my phone to use as screen savers and caller id's. some of them work as they are supposed to, some don't. it seems to be totally random, i've resized the pictures to one of the phones preset image sizes ie: 1289x960 and named them appropriately. My question is, why would i be able to assign some, and not others. they aren't overly big pictures (approx 200kb) any one else with this problem? anyone find a way to fix this issue?