Haha, I have this mouse, Check if you have the batterys in right, this certain mouse is a little weird, both Positive ends (+) are on the bottom, and both negatives (-) are both on the top.
Also, make sure the switch Isnt broken, you can experiment with the switch on the bottom while the faceplate is off to see how the switch pulls the trigger on the bottom, there should be a bar that slides up and down that pulls the trigger underneath the laser.