brake lights

[GaryBe]

my 2013 c4 grand picasso has developed a strange fault, the rear brake lights are out but the high level brake light works, have checked the bulbs and fuses all ok . only checked the 10 amp fuses in engine bay as i read somewhere the fuse should be ten amp . i checked the bulbs by removing them and connect to battery. any ideas

[Huskyxantia]

Check any part of the wiring loom that goes from boot lid to car body if it has a bend , these can have a broken wire inside , check also the earth points to the rear lights too