Is this the first rule listed in the alert configuration dialog box? Normally, if an alert isn't being triggered, it's because either the match parameters are not being met, or the message is hitting a rule further up in the alerts and getting matched on by that rule instead.
Your patterns look good - you can try setting the Message Type Pattern to ASA-3-713902 and seeing if that works. Also, check to make sure that the syslog service is running (obvious, I know). If you move this rule to the top of the list and do the other suggestions, try restarting the syslog service itself to see if that works.