Front right and left side marker not working -2010 glk 350
 

Voltage is present at socket. However, when the light bulb is installed, multimeter indicated voltage drops to zero. Light bulb tested good out of vehicle.
New bulbs also tried. Front fuses tested good.
Both left and right Marker light error messages on instrument cluster.
Anyone with substantial knowedge know what device might be bad other than the SAM?