Trying to rent a movie on Apple TV.

I am trying to rent a movie on Apple TV. I set up my shared itunes so it can see my computer but when I click to rent it tells me to go to itunes on my computer and verify payment. I have looked at my account and there is nothing in any carts. I have gone to my setting and added a credit card even though I already have more than enough of a balance to pay for the rental. help!!!