Avantguard 5, Sensor and Siren Issues

I recently installed an Avantguard 5 into a project truck.  Unfortunately, I am not satisfied with the security system... Let's just say "It's got issues." 

From the initial install, I've been unable to set the Prox. sensor sensitivity.  I figured it would be easier to just wait until my Clifnet cable came in for the laptop, so I waited.  Then I waited some more. Then I waited some more.  Over three months went by before my cable came in at the local shop!  Anyway, it did finally come in.  In the mean time, my siren stopped working! 

So, I hooked up the laptop and tried to test the siren.  To my amazment, the horn honked.  But wait... The Horn is NOT the Siren!  So I figured I'd go ahead and program the Prox. sensitivity.  But after searching and searching, I couldn't find a way to do anything with the Prox. sensor within the Clifnet Wizzard.  To say the least, I'm thouroughly disgusted by the whole ordeal.

I guess I have a few questions:

Has anyone had problems like this with the Avantguard 5? 

Is my problem the siren, or the proximity sensor, or the unit itself? 

Is it a "feature" of the system not to be user-friendly for adjusting the sensitivity on the proximity sensor?

Thanks everyone!

I never spliced into the Prox. so it's a factory plug-type connection.  So too is the connection to the siren.  I have re-connected each of these connections and checked for corrosion on the siren connector.  There seems to be nothing wrong with these two connections. 

I mis-spoke when I initialy wrote this post.  When I first installed the system, I had the Prox. sensor breathing.  But it stopped working by the time I had the truck on the road.

Any ideas?

Proximity Sensor placement is also important. Where did you place it?

I am not sure about the G5 series, but the G3 and G4 sirens needed the battery(in the siren) to be fully charged before the siren worked properly. This sometimes took a couple of days of driving as the siren would only charge when the car was on. I have done a couple of G3 and G4's, and sometimes the battery in the siren was fully charged out of the box, and sometimes it wasnt.