iPod touch wont charge on my computer

my ipod touch 4th gen. only charges with my computer. my 2nd gen. charges on my AC wall and car charger. I've done full reset, (holding down home and lock buttons process) which caused it to restore to default setting. then I restored it to the latest backup. it didn't do a single thing. it still doesn't work. what do I do? do I just give up and take it to a Genius tech? : |