No matter what brand of rinse aid I use, there's always a white film on glassware, dishes, etc. Is there something wrong with the dishwasher?What could be the problem?

Hello, W/D here.
We've had the same problem, and here's what we did to solve it.
Clean the dishwasher as best as possible. Place t cups of vinegar in the bottom of the tub, and run a hot cycle. The vinegar helps kill and remove the scum that can build up in the sump of the tub. If the spray arms are clogged, you can remove the debris with a paperclip or toothpick. (Check and do that regularly anyway).
Cut back on the detergent as far as you can, while still getting the dishes clean. I know this sounds a bit odd, but the amount of recommended soap is based on the dirtiest dishes, and the worst water possible. We rinse the major food particles off of our dishes before loading, so dried on food stuffs isn't an issue. We have cut our detergent to about 25% of the recommended amount, and the dishes still get very clean. We put a sprinkle on the door, a sprinkle in the dispenser cup, and close it up.
The detergent itself is abrasive, and can leave deposits on the dishes, most noticeably on the glassware. Cutting the amount of detergent, and using a good drying agent helps a lot.
Over a period of several cycles, the quality of the wash will improve. Don't expect to get to 25% of the amount of detergent right away. Cut it to 50% to start with, and adjust the amount based on your own observations.
Hope that this helped you. Best regards, --W/D--

The most common cause is calcium build up in the unit you will need to run some cleaner through the dishwasher. you can get dishwasher cleaner from any local store or parts store.You can also use any kind of calcium lime and scale remover run it on an empty cycle a couple of times to clean the system out. this may need to be done about once every three months depending on the use of the dishwasher.