[Closed] initialising mapping channels?

using polyops to set mapchannels as active or usable doesnt seem to work, i get
system exception
Does anyone know why this happens?

eg
polyOp.setMapSupport $ 2 true

polyOp.setMapSupport <Poly poly> <int mapChannel> <Boolean support>

polyOp.setNumMaps <Poly poly> <int count> keep:<boolean=true>

Thanks