Philips steam generator no steam coming through tube?

I have been given a philips steam generator iron which is only a few months old , it switches on lights up heats up , but when I press the steam button on the iron handle nothing happens. I have descaled it although it was only clean water I have cleared out the sole plate steam holes but still nothing. Should the tubing from the base to iron get hot when switched on and heating up as mine doesn't does this mean a blockage in the tubes and if so how do I sort it? It makes the pumping noise I regonise with my previous iron , would appreciate any help
Thank you