Hello,

I tried staring out with the default Cessna 172SP with engine on and avionics etc., then I load the CS 757, align the IRS, entering my FMC, set VNAV, take off and at 1000 ft AGL turn on the auto pilot to fly the route.  Well the auto pilot was enabled as I saw on the MCP, then the plane promptly drove to the ground.  What's happening here?

I search everywhere, but I could not find any text describing the correct use of this plane or to load and configure it properly.  I even downloaded the tutorial installer from another company, but since I bought mine from CS, it would not install.  The manuals is fine and detailed, but if I cannot start properly, what is the point?  

:(