Payment app not hitting the payment session url specified in the extension

[Punarvasu]

I have created offline payment provider app, I have created extension that is approved and published.

But when i am testing the app on development store its not hitting the Payment session URL specified in Extension configuration.
I have also set up SSL on my  apache server, still its not going on that url after checkout. In front end on development Store m getting this ERROR - Your payment can’t be processed for technical reasons. Try again or use a different payment method.
For Info: there is only simple code in payment Session url
$rawdata = file_get_contents("php://input");
$order_info = json_decode($rawdata, true);

print_r($order_info);die();

Please help -