I have a kenmore dishwasher approx. 3 years old. The dishes don't come clean and the soap remains in the cups. What could this be. Thanks

It sounds like there is some kind of restriction in the arms where the water should come out. Take a toothpick and clean out each one of the little holes on the arm, both upper and lower arm (if you have an upper arm that is). That should solve the problem as you don't seem to be getting enough water to dissolve the soap.