Tefal pro express anti calc steam iron?

Hi. I have a Tefal pro express steam iron and the steam button appears to have stopped working. When I pressed the steam button it made some clicking sounds (the same sound it makes when it has run out of water and you press the steam button). I have drained the anti-calc collector (even though the anti-calc light hadn't come on to say it needed doing) but it is still not steaming. Any ideas? Thanks.