Auto Jump with the logic bricks arn't working

Ok, I have the auto jump bricks for all objects set up exactly like Crays and I don’t understand why it doesn’t work. I have an empty on the back called ground_back with a Ray Sensor, 1.80 Distance on the -Z axis with Inv enabled and X. They are both connected to an expression, which is connected to a change state. I have a property called moving and when the box is moving it turns to one. All the sensors are named exactly like they are in the epresstion, but it doesn’t change to the another state. Here’s the blend file:
http://download726.mediafire.com/iygz9mwtmydg/e4wiiywyh5j/GameV0.1Test.blend

Thanks for all the help guys.

the template about Cray is more complex. Anywere your problem is due to the fact that your script does not set a force which acts on Z axis

Cray doesn’t set a force on the Z axis ethier, my problem is that it’s not going to the state I want to go to. I know how Crays script works, and it doesn’t have a jump thing in it, it’s only for direction and movement not jumping. Plus, I deleted all the unneeded logic bricks on Crays Template and properties to see if the auto jump still worked. It does, I have a problem with the rays, not the script not the expression and not the properties. I just don’t know how to set up the Ray like he did.