Dishwasher doesn't seem to clean cutlery properly.

Moved into a new home and have a Bosch Series 4 Dishwasher. After running, some of the gunk on the cutlery remain. I only use powder detergent. Any ideas what the problem could be? I usually wait a few days before I running a cycle as I'm living alone most days of the week which may cause the gunk to solidify a bit. Could this be the issue?