I assume you mean that you have replaced the main belt around the drum. If so then you may have assembled it wrong. There is usually a contact switch mounted on the base of the dryer. The large spring to tension the belt goes from the belt tensioner idle pulley and the other end hooks over the contact switch and pulls the two halves together to make a contact. This will then feed power to the element. If the belt breaks or comes off, the switch will spring open & stop the element from heating.
Lincoln Appliance NZ
May 2009