Paytm for PMPRO showing Payment failed

I want to create a LMS Membership website. I have used PMPro and Paytm gateway for the subscription. When I try to pay through Paytm its showing payment failed error [Payment failed. Emails sent to and [admin email]”0] error at the time of checkout. i am using test API Key for the development purpose. Please help.

Here is the link of checkout form.

https://tuitionline.in/membership-account/membership-checkout/?level=1