Stinger 310 alarm problem

Have a problem with a Stinger 310 caravan alarm . It arms and disarms from the key fob ok and will go off with tested but whereas the side repeaters and front and rear road lights used flash to confirm armed/disarmed , these no longer do so...They were working when I last had reason to notice them, and the caravan has not been used...When hooked up to the car all roadlights are working fine...Checked fuse number 12 in the Sargent unit which I think supplies a 12volt supply to the alarm, and it's fine...Someone suggested that the 12 volt supply may not be getting to the alarm unit and that it's working off it's stand-bye battery in which case the marker lights etc would not flash...I'm not too sure about checking out this possible electrical as the cause...Can anyone tell me if they have had this problem and what did they do to cure it.