Facebook app, js sdk, fb.ui( {method:pay} ). Error calling method?

Question

JavaScript

developers.facebook.com/docs/creditsapi/ - see the Payment Prompt example here.
When you click on the link and call fb.ui( {method:pay} ) the fb script calls apps.facebook.com/fbml/ajax/uiserver.php?__a=1 , which should request my credit url and display the payment interface. But, this does not happen, and I get the message “An error occurred. Please try later". I press ok, the message repeats.
The fact is that the payment was integrated on October 12th, after which I was distracted by something else. When I returned to payment integration, it no longer worked.
Naturally, the conclusion follows, it is possible that this is caused by changes made to the application. But from the code here is a link and a call to the fb-api method.
Perhaps this is due to the innovations of fb, or this is my terrible stupidity. Perhaps the matter is in the application settings, but I did not find anything in the docks.
Link to the application - apps.facebook.com/256530591058381/
If you look at the html code, there is a link to call the payment window (it is not visible, you need to remove the flash to be able to click).
Hope you can help. Thanks

Answer 1

I found a somewhat complicated example of payment, compared the given parameters. It turned out that when calling the same fb.ui method, one parameter is not sent from my application - app_id. Adding this parameter to the passed object helped
var obj = {
method: 'pay',
order_info: { order_id : objData.id },
purchase_type: 'item',
app_id: ' _ здесь_ ',
dev_purchase_params: {'oscif': true}
};
FB.ui(obj, callBackPay );