[Faisal_khan]

It Must be:

pawn Код:

public OnPlayerKeyStateChange(playerid, newkeys, oldkeys)
{
    if (newkeys == KEY_YES)
    {
        new vehicleid; // u missed new here
        vehicleid = GetPlayerVehicleID(playerid);    
        if(GetVehicleModel(vehicleid) == 597) 
        {
//these lines are secret
        }
        else
        {
            return 0;
        }
    }
    return 1;
}

Thank you its working +rep.