Tail light and side light not working

[HIGHLANDMERC]

320CLK W208 2002. The nearside tail light and the nearside front sidelight are not working. Bulbs OK. Could not detect 12 volts supplying the tail light. Tested with a bridging wire from the offside tail light and the bulb lit. Problem seems to be no supply voltage being supplied to the nearside lights. Any advice or suggestions much appreciated.