my 2008 dodge charger alarm dont work what could be the problem?

How soon after the break in did you get to the car? Was it overnight? A couple hours while at the mall, etc? Perhaps the alarm DID go off, however, most alarms will auto-shut off after a certain amount of time. (Perhaps to save battery,etc?) You can test your car's alarm system. Close and lock the doors and set the alarm, then reach in through the open window and try opening the door from within. This usually sets off the alarm (i.e. At the gas station, I will close the vehicle and set the alarm while pumping gas. If one of my children inside tries opening the door to get out, it will set off the alarm and I will be able to hear it while inside the station.)