I'm not using ldirector for MySQL, however you could just try the following:
virtual = 192.168.12.10:3306
real = 192.168.12.3:3306 gate 1
real = 192.168.12.2:3306 gate 2
Try just that without all the negotiate stuff. If it polls tcp:3306 and nothing answers, it's going to fail out. I'm sure there are advantages to doing a full on negotiated connection but for the time being (just to get it to work) simple TCP should do the trick.
Like I said, never tried it with MySQL but I mean it IS just a service