Point Def. too tough against missiles-change it.

[Nitram Draw]

I use a lot of AAA destroyers and cruisers. Each usually has between 12-20 PD weapons. Very few missles or fighters get through in a fleet with 2-3 of these attached.
One problem with missles is the rate of fire. Firing every 2-3 turns makes it easier for the PD weapons to do their work. As Arralen points out the key to attacking with missles is to overwhelm the defenses. Perhaps a lighter damaged/shorter range missle with a rate of fire of 1 would help balance it out.