Need help with hdfc ccavenue payment gateway

Hi I am new to Magento and

I was developing the site with hdfc payment gateway

installed the extension given by hdfc bank but I got error sometimes

sometimes it goes back to success page but sometimes

it takes me to there has been an error processing your request page

I haven’t changed anything in Magento core or extension

also, there is no log in exception.log

help me to solve thank you!