iPad not charging when connected to computer, why?

I just recently bought a mini ipad, but when I connect it to my computer it says its not charging. This isnt the only problem, the computer doesnt even recognize the ipad therefore I cannot transfer any photos from my pc to the ipad. The funny thing is that itunes does recognize it. I have tried other USB cables and computers. What can I do? Any tips or recommendations would be very helpful.....Thank You!