My new alarm is acting funny.

Hello all,

I just installed a used Alarm box and the remote works fine. The problem I have is that the alarm function does not seem to work.. The alarm would go into programing mode, it will lock and unlock the doors (and turn on the interior lights). The problem is that when I arm the alarm, the horn chirps 4 times quickly. It's the same when you arm or disarm. When I unlock the door from the outside, through the window, and then open the door, the alarm does not go off. Is this indicative of a bad alarm, or did I not do something correctly? Thanks.

Clarke