Photostreams from Aperture working with one iPad, not another
I've been created a Photostream in Aperture and while it appears in my iPad 3, it does not appear in my other iPad 2 (model A1219). I've verfied that Photostream is set to ON, and the software is up to date. I also notice that in Settings>General>iTunes WiFi Sync, the "Sync Now" button is greyed out, even though my iMac is on, and the wireless network is working fine. Any ideas? I've attached a couple of screen shots of iTunes so you can see what's enabled.
iPad 2, iOS 5.1.1