Lighter fuses

I have 3 light ports in my 2006 Chevrolet trailblazer and 2 don't work. I have 2 upfront and 1 in the rear. i know fuse 13 is supposed to go to the lights. but i have 1 front and the rear ones out are there any other fuses that go to the lighters and why would one be out and not both ones upfront???