sigma m34 fitted to a motor home by motor mods ltd 1310296?

The Alarm will not allow the engine to start,sounded normal when I switched it off on the key fob,I have read the instruction book supplied with the alarm, tried every thing it suggested, cleaned battery terminals and all other connections,checked condition,found fully charged,reconnected power,let it stand both unset and set no improvement.please can you help. The alarm twitters when I try to start engine.