what alrm system is it? does it have 2 way capabilities? if it does then does it read anything different when it wil start or does not start. Was teh shop that installed it certified or was it al's alarm shop running out of the home from a guy who knows a guy about electronics cuz he went to school and dropped out 10 years ago.
Do you have the alarm manuals, does it flash the parking lights to give you an error code?
have you tried going back to them, contacting the manufacturer at all? Does everything else work?
Provide some details and hopefully we can narrow it down.