I have checked the private key in your control panel, and it indeed doesn’t match the SSL certificate we obtained for you from GoGetSSL.
When we give you a private key and SSL, you need to copy the private key from the client area and click the Upload Key button.
Right now, I see a different key in the box, as well as a CSR that was generated for the domain. That means you used the “Generate Key / CSR” functionality instead. That will overwrite the existing private key with a different one, which doesn’t match the SSL certificate. And if you’re using our certificate, the client area generates the private key for you, you don’t need to generate one from the control panel.
So please install the private key from the client area first, and then try uploading the certificate: