Enable logging.
Presumably you have other rules that allow LAN access to this SQL service? Is it confirmed that SQL is definitely listening for connections?
Surely that external address will be nat'ed to a local address on your firewall, so the server never actually see's the real external address hence the rule not working.
Why aren't you doing this at your perimeter firewall then, as opposed to on the server itself? Unless I'm missing something...?
Looks like abit of a mess to be honest.
I take it you are specifying a range, is this correct? (I havnt got time to work it out)
Is it in the right group (Outbound or inbound rule)?