missionMarker = createMarker ( -1305.2, -120.3, 13.4, "cylinder", 2, 0, 255, 255, 170 ) 
function createMissionMarker() 
    missionBlip = createBlipAttachedTo(missionMarker,19) 
    outputChatBox( "[Plane Mission] Älä vielä mene lentokone missionille. se on kesken", source, 0, 255, 255 ) 
end 
addEventHandler("onResourceStart", resourceRoot, createMissionMarker) 
  
function MarkerHit( hitElement, matchingDimension ) 
    local plane = createVehicle ( 519, 70.21049, -233.00739, 2.33665 ) 
    warpPedIntoVehicle ( 'hitElement, plane ) 
    outputChatBox( "[Plane Mission] Test", source, 0, 255, 255 ) 
end 
addEventHandler("onMarkerHit", missionMarker, MarkerHit) 
  
  
 
 
 
You got a typo there, remove the ' before hitElement.