Might be a blockage in the outlet from the tub. There will be a hose that comes from the tub down to the drain pump. It will need to be taken off and the opening in the tub checked and the hose checked. If everything is clear then either the drain pump is faulty and pumping too slow or it is not running at all. If the pump does not run then it could be a faulty pump or a power supply problem i.e. fault on main control board
Lincoln Appliance NZ, November 2014