WHCMS WP Integration throwing an error

I have set this up and put in all the details...

But when I click on "order" link, I get the following error:

Sorry this doesn't look like a WHMCS site at [http://hosting.blogstarta.com/members/] Make sure your WHMCS Integration settings are pointing to the correct URL and that the WHMCS site is set for the Portal template in Setup | General.

The installation IS on that URL (you can verify by visiting the link) and the portal template is selected (as seen in my Gen Setting on WHMCS).

What gives? Please help. Thanks