cb antennia mount help needed

my brother has a 2009 Jeep rubicon ,
firestik 2 antennia ,

he can send and recieve but only for 2 blocks max , we have anotehr guy thats across the river from us maybe 2 miles away , my brother cant hear him at all , but when i unscrew the end of cable and leave only the + positive side into the radio boom he can pick up the guy across the river loud and clear . as soon as we screw on the ground to the radio , boom we can barlly hear him , with it connected and my brother talks he sounds like he is verry overmodulated , and maxing out.

i tried a totally different cable and radio as well , with the same results

all equipment is brand new.

the mount we have it painted black we scraped away the paint on it and attached a ground wire to it then rain it inside the keep near the back scrathced pain and screwed it on.

i know a ground helps from mout to frame or somthign but it shoulnt give this much of a difference that we have.

looking for a little insight to this problem as we are at a loss.




this is the order we have the antennia attached to the mout


http://www.tacomaworld.com/gallery/data/500/medium/CB_mount.jpg

not my pic bu the order is the same ,
plastic washer metal flat washer then locking washer all ontop of the mount.

thanks in advance

 

its mounted same way as in the picture , with a ground wire to the cubby hole insdie the jeep where we scraped off paint its metal and i tested the ground with ohm meter all is good , ,tested ground , tested antennia wire both ends with ohm meter , no shorts at at all also tested the antennia mount itself where the antennia screws into , that all tests fine to .

 

arug , tested out the mount again and drilled the hole bigger , the small indent on the plastic washer want sitting in the hole thank you for all the great help all i trully really really appreciate all your time and effort