Pay with a like plugin is not working

Hi,

I installed pay with a like on http://www.mapsmarker.com/get-a-coupon-with-a-like/ - unfortunately it is not showing the protected content after sharing.

I tried facebook like and tweet both with the same negative result - I am still seeing the sharing buttons (although a tweet got send out for example).

I am using WordPress 3.6.1; already disabled all other plugin - with no result. Switching theme is not an option on this site.
please help,
Thx,

Robert