Issues with Payezy plug in. Invalid Server Error

Hi,

I'm trying to make the integration using the plug in WooCommerce First Data Payeezy Gateway v 3.7.2 with WooCommerce 2.6.2

The issue I have is I get an Invaild Server Error when I try to submit a transaction. I have double checked to have the info correctly.

Am I doing something wrong?

Any suggestions on how I can successfully integrate it?