Really Simple SSL plugin

So, I installed “Really Simple SSL” and I got this report after a few days (nothing really changes apart from a few new pages:

“Really Simple SSL failed to detect a valid SSL certificate. If you do have an SSL certificate, try to reload this page over https by clicking this button:”

What might be the cause of this?

Have you Got an SSL certificate?

First, Buy an SSL certificate and use the instruction provided by the provider to is install an SSL certificate for your website domain.
The error message “Really Simple SSL failed to detect a valid SSL certificate. If you do have an SSL certificate, try to reload this page over https by clicking this button:” suggest that it is unable to detect the certificate.

You have to install the SSL certificate properly to fix the issue.