The pilot stated that he was level cruise at 10,500 feet mean sea level, when he moved the fuel selector from the right tank to the left tank. The airplane was equipped with the Beech fuel selector valve disengagement warning light kit. The fuel selector is a combined fuel pump and valve assembly. The handle can be lifted up and down to pump fuel, but in this condition it is not engaged with the selector valve portion of the assembly. When the fuel selector handle and the fuel valve do not agree, the red 'fuel' light illuminates. When the pilot selected the left tank the red 'fuel' light illuminated. He cross checked the fuel flow and fuel pressure, both of which were in the normal range. A few minutes later he entered an en-route descent, when the engine began to lose power. He pumped the fuel pump, the red 'fuel' light remained ON, and the engine did not regain power. The pilot executed a forced landing onto a road and damaged the left wing during the landing roll. A post accident examination of the airplane was performed by a Federal Aviation Administration inspector and a technical representative from the airplane manufacturer. The fuel selector valve was found to operate as designed. The red 'fuel' light illuminated when the fuel selector handle was not engaged with the valve and aligned with the fuel tank that provides fuel to the engine. Additionally, the engine was test run and found to operate normally.