Cannot restore previous iTunes purchases.
I am trying to download prior iTunes music purchases to my new MBA. I have bought music from iTunes on other devices (iPhones, iPads, PCs) all using the same user name. I followed the instructions at http://support.apple.com/kb/ht2519 , but am not seeing anything populate my Music list. Any thoughts on this? I am new to OSX and the Apple community, so any help would be appreciated. I just want to get all of my old music purchases downloaded to my new computer.
MacBook Air (13-inch Mid 2013), OS X Mountain Lion (10.8.4)