It is my understanding that there are two types of SSL. Shared SSL and Dedicated SSL. Most of the "FREE" SSL you see advertised as SSL ready is a shared certificate and it is for the shared server. With this you can do Amazon Pay, Paypal, etc. But to actually take CC info ON YOUR SITE (collect cc info) and process cards yourself you must have Dedicated SSL. Search the web for both terms "Shared SSL" and "Dedicated SSL."
I maintain a site that takes and collects card info. We had to get a dedicated SSL to get card processing.
I am not an expert... your experience may vary.