Instrument lights not working on 99 volvo s70

My instrument lights and shifter lights do not work. All the idiot lights work, heated seat lights, visor mirror lights work as well as lights above the mirror. Glove box light worls as do courtesy lights. All out side lights work/headlights, blinkers etc. Radio light also works. Fuse is fine and the dimmer switch has no effect. Also, turning the headlight switch to different positions has no effect. I just had the oil changed at the volvo dealership. Could a software upgrade have any effect? If not, then the dimmer switch must be defective? Anyone think of anything else? Thanks.

The dimmer switch could be the problem, it also could be a bad ground to the instrument panel. In a modern car a software update could cause a problem, but it would not be high on my list of suspects.