Soap does not desolve

Question

I am have a problem with my dishwasher where the soap does not desolve. We use a liquid soap and have tried tablets. The main latch door does open during the cycles but when everything is finished and we open the dishwasher either the tablet is laying at the bottom of the dishwasher or the liquid soap is running down the side of the dishwasher. Where do I start troubleshooting this one at?