Hi Guys.
When i load a flight into the fmc (completly loaded)everthings is fine.
But after take off engaging vnav,lnav,cmd LNAV wont engage the flightplan everything else is working fine like vnav etc .and even on lnav iam still able to turn the aircraft manually with the yoke.

Any suggestion.
Thanks
and sorry for my  bad english.

Do you activate the flight in the FMC? After loading a flight plan, the FMC should ask you to activate it. Hit that button, then after finishing the rest of the programming, hit the Exec.