This problem drove my parents
nuts for weeks. They purchased a home at the lake. Upon using the dishwasher
it fail to clean the dishes and it left a soap residue. After several repairmen
tried and failed, we discovered the problem. The vacation home was purchased with all the furnishings including
the dishwasher soap. The soap was too old. Who knew? They put expiration
dates on milk and other things but not on dishwasher soap. Dishwasher soap
goes bad with time and it apparently doesn't dissolve properly then fails
to clean. So just get some fresh dishwasher soap and you're home clean.