i have my pro-96 programmed with fort worths public safty Motorola Type II Smartnet,i only entered the control channels,trunking is on,and the scanners trunks just fine,but thers one frequency that when it stops on has a loud screaching sound,and i can still hear the conversation in the back ground,and its the only frequency that does it(867.21250)all others are nice and clear,this is a very anoying problem and i dont no how to fix it,any sugestions ?