Your dishwasher needs to stand level and balanced on its feet to function properly. Try rocking the appliance from side to side or back and forth. If it is wobbling too much, your flooring or the appliance's feet may be uneven.
Use a spirit level to check the appliance's balance. If it's off, adjust the feet by reaching under the appliance and finding the lock nuts on the feet. Turn the feet clockwise or anti-clockwise, until they are firmly in contact with the floor. Tighten all lock nuts again by hand.