Bosch TDS£360GB steam iron generator?

i have a Bosch TDS£360GB steam iron generator which i purchased 3 years ago - the steam is not working - i have put distilled water in for a few minutes and it still does not work - any suggestions - please note: it works in term of it gets hot however the steam part does not work - the green light comes on them goes off again - i can hear it click but then it does not work still