CHP Radio Freq. in the foothills!??

Hey guys I have been having a hard time trying to figure this out. I live in El Dorado Hills and listen to the CHP Green - Base and Mobile - Auburn (45) / Grass Valley (42) / Placerville (44) radio frequencies. I have a 15 inch magnetic antenna mounted outside my house. It works fine for all the Sheriff, Cal Fire Camino dispatch/eldo cmmnd/amador cmnd/calstar, but when ever I listen for chp traffic I will hear like once or twice a dispatcher in a conversation with a unit but I wont hear the unit. I know the chp radio setup it kinda of wierd. The funny thing is I tuned into CHP Black 3 - Base and mobile - South Sacramento (112) / Woodland (47) / Rancho Cordova (58) I can hear every conversation. Whats the deal, can somebody help? Thanks

CHP Radio Freq. in the foothills!??