alarm not responding to key fob?

i have acitreon xantia 1997 19 td it,s not a transponder key as i have a key pad imobiliser linked to fuel shut of solinoied factory fitted the fob works,had it tested good strong signal switch blade key fob 2 button top button locks car then press bottom 1 to deadlock and arm alarm no response at all thought,might need reprograming any answers with,great thanks???