[[KHK]Khalid]

This is not how the operator || is used (To know how, click me). You should of used "," instead of it if you wanna save lines, like this:

pawn Код:

public OnPlayerEnterVehicle(playerid, vehicleid, ispassenger)
{
    new model = GetVehicleModel(vehicleid);
    if(model == 541)
    {
    if (GetPlayerSkin(playerid) != 0 ) return SendClientMessage(playerid, -1, "You may not drive this vehicle!"), RemovePlayerFromVehicle(playerid);
    }
    return 1;
}

But, this still won't work because you're using RemovePlayerFromVehicle under OnPlayerEnterVehicle which is called before a player enters a vehicle (Actually as soon as they press RETURN), so RemovePlayerFromVehicle won't have effects as the player hasn't entered the vehicle yet. If I were you, I'd do it this way:

pawn Код:

public OnPlayerEnterVehicle(playerid, vehicleid, ispassenger)
{
    new model = GetVehicleModel(vehicleid);
    if(model == 541)
    {
        if (GetPlayerSkin(playerid) != 0 )
        {
            SendClientMessage(playerid, -1, "You may not drive this vehicle!");
            TogglePlayerControllable(playerid, false); // freezes the player
            TogglePlayerControllable(playerid, true); // then unfreezes him, which will cause him to stop the entering animation (and won't enter the vehicle)
            return 1;
        }
    }
    return 1;
}