I'm using iPhoto on my Mac, and am having difficulties purchasing a created Calendar. The program is asking for my Shipping Address, but that doesn't to work...

What about it doesn't work? Do you get an error message? If so what is it?

Remember the shipping address and credit card billing address must be in the same country. Also the selected Print Products Store must be the same country as the two addresses.

Also if you have the letter "p" followed anywhere by the letter "o"replace the "o" with zero. There's a bug in the ordering process that if there's a p followed by an o anywhere (doesn't have to be immediately following) the software thinks it's a P.O. box and won't accept it.