The car don't start.

turn key on put in nutral leave in nutral turn key of and then start

I have the same Mercedes as your self 1999 E320, and my car started to crank but not turn over , and it will not start, what did you eventually do to resolve the problem? I was told that I need to change the crankshaft positioning sensor. is that what you had to do? please answer back as this problem driving me crazy.