The steam tank may not be heating because of mineral deposits in the tank. But also do this check first. Open up the tank reservoir cold, and drain all water out, (is it clean inside there when you shine flashlight in there? Rinse with clear filtered water only (low minerals).
Do not use CLR or anything agressive in there. You should have the main unit in full steam mode and the iron control also in full steam mode. Leave one tablespoon of water in the tank, put back together and let the pressure build. Put a clean towel on your ironing board and when iron is at full pressure and heat, hit the burst of steam and look at what comes out of the sole plate. If you see lots of white deposits look at the sole plate and see if the white chunks are coming out steam holes.
When using iron, run it till steam/water tanks are dry, the burst of steam is used in this case to clean the iron of all standing water. Pull the reservoir and allow to cool...once tank is cool drain it as well. Doing this several times should help purge unit of the heavy mineral deposits.
If you need parts, here is the Rowenta repair facility....
California Electric Service
in Concord CA (it is the only Rowenta repair station in California) go to either of the following addresses:
their website is: http://www.californiaelectricservice.com/
or tech service: email@example.com