[mineralo]

it should work, you maybe forgot to write stuff OnPlayerEnterVehicle
write something like this:

pawn Code:

public OnPlayerEnterVehicle(playerid, vehicleid, ispassenger)
{
    if(ispassenger == 0)
    {
if locked 
{
GetPlayerPos(playerid,Float:LocX,Float:LocY,Float:LocZ);
            SetPlayerPos(playerid,Float:LocX,Float:LocY,Float:LocZ);
            SendClientMessage(playerid,COLOR_GREY,"( ! ) This vehicle is locked by the owner !");
}
}
}return 1;
}