my computer is authorized.. but iTunes wont transfer my purchases from my iPhone to my computer. help!

ive authorized, deauthorized, reauthorized, and every combination of the 3 you can think of in the last hour, and no matter how many times i authorize my computer, iTunes still says that i need to authorize my computer in order to transfer my purchases.. i dont understand what im doing wrong, this is not making any sense. i even deauthorized, rebooted, authorized, rebooted, and it still says i need to authorize my computer. help me please!!