I have problem with the Payment Gateway

Yesterday I made the installation and setting for this plugin, but when I went to payment setting. I activie payment method Paypal. I took the information then when I clicked the button to save, it redirected me to a page that is this one: http://developpementpersonnel.ca/wp-admin/admin.php?page=membershipgateways

It is written: Do you really want to do this? Please try again.

It's Ignacio who told me to run here. :stuck_out_tongue: