On my Nexus 7, I keep getting
An error occurred. Please try again.
Over and over when attempting to buy any paid apps on the Google Play store. It works fine for free apps, but always returns this same error when I try to buy a paid app. I've "tried again" a dozen times with the same result.
I checked my Google account and the Nexus 7 shows up as properly attached to my account. It also works OK in Mail, Calendar, and the other bundled Google apps on the device.
I don't understand why I'm getting this error, which tells me nothing. I'd like to buy some Android apps for my Nexus 7, but I can't!
Based on one of the comments, I tried buying the same app on the Google Play website, and I get an odd message next to the Nexus 7 (which does show up in the list of devices for me):
You have not opened the Google Play Store app recently on this device. Please open it and try again.
But, but, but I have the Google Play store open right now on my device!