Using google I found a number of reports and different fixes for this problem.
The easiest one to try is to go into android settings - apps - all - Google play services and clear data.
If that doesn't work then report back.
Also it would be helpful if you would provide info on your Droidbox model, if this problem has only just started happening, android version and so on.
Might worth trying to Clear the Data/Cache of the Google Play Store, also the Data/Cache of the Google Play Services.
Reboot your device, login into the Google Play Store, and give it a go.
However; Also make sure you don't have any age-restriction rule on your Google Account