Had the same problem, replaced the heater unit at the back but still not working then replaced the thermostat housed inside the front of the drum above the door (2 screws hold the plastic cover in place) now its working fine. Suggest you link out this thermostat first to see if the element heats up, if so thats your problem (as the thermostat is much cheaper than the heater unit) otherwise its likely to be the heater itself.
Hope this helps
Alan, February 2007