Authorize.net Plugin Error

I am using authorize.net payment gateway plugin but its showing error at the time of order payment ,

An error occurred while trying to report this transaction to the merchant. An e-mail has been sent to the merchant informing them of the error. The following is the result of the attempt to charge your credit card.

This transaction has been approved.

It is advisable for you to contact the merchant to verify that you will receive the product or service.

I think there is problem with the URL .
Please help me out on this .

Thanks