I had a starting problem with my 99 E300D. When I would turn the key to position 1 or 2 everything was normal. Then after the glow plug light went out I would turn the key to start the car and nothing would happen.

I'm not sure if your problem is the same.

The problem I had was with the ignition switch. I needed to have the dealer replace it so they could program the switch to my car and key. I have not had a problem since and its been at least 5 years ago.