ipad can't download songs from itunes

I have multiple iPads, Ipod Touchs and iPhones. On one of my ipad 2s running 6.0.1 I go to itunes to download previously purchased songs and next to each song is a button that's greyed out and only contains the letters "DOW". The song isn't downloaded and it can be downloaded from other devices. Also, when in iTunes on the iPad all the songs show the prices but they are greyed out too. I can't buy anything. Weirder, when I go on the ipad to purchased music in iTunes, I can find just a few songs that have the cloud icon that i can download. BTW, this is Wifi only ipad 2 cannected to my internal WLAN.

Little help, this is frustrating.

Thanks