A use of ShopTab's "Promote" button requires some additional permissions from Facebook that may not be in your profile if you had a store with ShopTab prior to January 15, 2013. This is easily fixed by removing and reattaching the app via our "Facebook" tab. Follow the instructions below.
1) Log into ShopTab and select the "Settings" and then "Facebook" option.
2) Select to "Remove" the app from your page.
3) Immediately click on "Connect" to reapply the app to the page. This may prompt a dialog from Facebook asking your permission to use this features permissions. Accept this and the app should be active on your page once the connection is completed.
Now try your promote and it should be placed on your News Feed.