When you create a new app on Facebook, the 'Sandbox' mode is activated by default. This way, only the app and fan page administrators will be able to access the promotion.

You need to deactivate the Sandbox mode. Please, follow these instructions:

  1. Go to https://developers.facebook.com/ 
  2. Click on "Apps" and select the app you are working in.
  3. Click "Show" on Dashboard, where you'll see the App ID and the App Secret . To deactivate the Sandbox mode, you need to fill out the field "Contact email" on  "Settings". 

  4. Once this field is complete, go to "Status and review", where you'll read: "Do you want to make this app and all its live features available to the general public?". Just mark "yes" and your app will be visible for everybody. 

Facebook won't allow us to do it automatically :-(