When the dishwasher cycle is started, the soap dispenses, but water is not coming out of the spray arm at the bottom of the dishwasher. The soap cakes up and sits at the bottom of the dishwasher. The dishwasher runs through the complete cycle, but the dishes are not clean, due to the lack of water coming out. The water valve is open.
Very likely the problem is a bad or clogged chopper (#6 on the diagram).
You can find more useful information in one of our previous threads: http://forum.appliancepartspros.com/dishwasher-repair/2903-whirlpool-dishwasher.html
If you would need the correct part numbers or more advices, post the end of the model number.
Gene.