Ok, if the door strike is good, then it can ONLY be TWO parts causing it, the door latch switch OR machine control board.
If you replaced them both already, then one is bad right off the bat, lets ohm test the door latch switch first to see if that's good. You will need a multimeter to ohm test it.
--->Here's the machine control board for your model:
WD21X24901 Machine Control
Here's the door latch switch for your model:
WD21X10490 Latch Switch
Follow the directions here:
Door closed: 0 ohms.
Door open: infinite ohms.
Let us know what you find. Make sure you disconnect power to the dishwasher before ohm testing.
Jake