I m having the same error, except that the plugin was working till a few days ago. In the mean while I have updated woocommerce to 2.2.8 and thought that this might have caused the problem. But the plugin did not work even when I installed 2.2.7 woocommerce version.
I have checked the Merchant ID, Working key and access code and ccavenue is the only payment gateway active.
See product page at https://iipta.com/ip101-registration/#enroll
Please do let me know what wrong I must be doing or what I can do to fix this problem.
