Play store icon in App drawer disabled in Nexus 7 i use the stock rom JB 4.1 on Nexus 7 8G.
There is a small play store icon in the top-right corner in app drawer(not app icons in ap drawer).

i found that the icon in my cm10 version phone and my friend's nexus 7 can be clicked and open play store directly, but mine wont work.
just as it is disabled.

why? how to enable it?
From previous experience, rebooting the device should fix the issue.