The actuator is not the source of the signal. The cam position sensors tell the DME where the cams are in realation to the output of the crank sensor. I'm not sure why the Durametric does not see the other sensor, but it could be fried or disconnected.
Each cylinder head has one, item #34 in the attached:
Shown here is the camshaft position sensor. There is one located on the top of the left cylinder head towards the front, and one on the right cylinder head towards the rear for the 5-chain motors used up to about 2001. For 2002 and later 3-chain motors, the sensor is located on the top of the left cylinder head towards the rear, and on the right cylinder head towards the front.
