Facebook Credits. Error 1151

I'm developing an application on Facebook, and I need to have the possibility to integrate my application on other sites (with connections to Facebook by the Facebook JavaScript API).

On Facebook, I can buy some things on an application using Facebook Credits, but on some other site, when I call the Facebook purchase dialog, I get this error:

API Error Code: 1151
API Error Description: Sorry, but this app may not be eligible to accept Facebook Credits.  
If this app has accepted credits before, please try again.
Error Message: Invali开发者_如何学God Application

Or is there a Facebook purchase dialog we can use only on Facebook?

---

This happens because the payment interface can only be called from an iframe application running on Facebook.