how can i fix no sound on my alarm ?

mondy st24 - central lockin seems fine, done bonnet pin switch alarm test mode and get sound to the horn in boot. Driver door does beep once but other doors dont. surely thers something simpler than taking all other door cards off to check all those switches. As i say the centrl lockin seems fine with fob and lights do flash when you do lock test leaving window open but then lean in and put key in ignish the hazzards flash but no alarm sound. Any ideas?? thankyou so much in advance. justin