Are the targets infront of it? The guns are placed around,s o to use all 5 there has to be stuff to shoot at behind the ship as well as in front.

Kharma's right. the starfish are a wee bit cranky with the range stuff. try moving them forward a nudge and they might rotate a bit and get the firing angle right on more of their weapon batteries. i find that most of the time they fire with 3 turrets at once. if you want to see them unleash all 5 you have to manually maneuver them to be right in the middle of a cluster of structures. 

The Adjudicator only has weapons on the front bank. So the structures need to be clustered together since weapons have a firing angle and can't shoot at anything outside the arc.