A rear tail light housing can fail causing the brake light on the affected side to be inoperative. Replacing the failed housing is commonly required to correct this issue.Google+
Car Problem Reports
Mercedes-Benz C280 Brake Lights May Not Operate Due to Failed Rear Tail Light Housings
Mercedes-Benz C280 Problem
Average Mileage: 127,050 mi (74,000 mi - 155,300 mi)
Visitor, 1999 Mercedes-Benz C280, 135,000 mi
Left rear brake lights don't work even with new bulbs.
Tail light and blinker on rear left side do not work.
Visitor, 1996 Mercedes-Benz C280, 111,000 mi
Brake light are not working got a new switch but nothing
Visitor, 1997 Mercedes-Benz C280, 147,000 mi
tail light on drivers and 3rd light keep going out i fix one and remove and the other one goes out.