WHMCS Integration: Failure when receiving data from the peer

Dear Sir / Madam,

I am attempting to Integrate WHMCS in to my WordPress site and I am confident I have followed your detailed instructions in setting it up, however I am getting a "WHMCS Integration: Failure when receiving data from the peer" notice.

My WHMCS is setup at http://westcoasthosts.co.uk/billing & my WordPress site is setup at http://westcoasthosts.co.uk

I have created a username and password for you to login in to WHMCS admin to make sure I have definitely set it up properly (which I will share with you once you email me)

+ I will make sure you can access the WordPress site as well.

I am usually able to set these things up, but I am really having an issue with it at the moment.

Kind Regards,

Sam