Q: can't buy songs from itunes

when I go into the Itunes store, I click on the "$1.29 buy" button but nothing happens.  I have $30 on my account, so I have plenty of money left.  I have itunes version 10.7.0.21.  I've tried several times to close and open itunes but this does absolutely nothing.  Anybody know what the problem/solution is?

Thanks!