[justsomeguy]

i'd suggest you use this maybe?:

pawn Code:

public OnPlayerConnect(playerid)
{
    new keys, ud, lr;
    GetPlayerKeys(playerid, keys, ud, lr);
    if((ud != 128 && ud != 0 && ud != -128) || (lr != 128 && lr != 0 && lr != -128))
        SendClientMessage(playerid, 0x0FFFFFFA, "JOYPADDER!");
    else
        SendClientMessage(playerid, 0x0FFFFFFA, "Not a joypadder.");
        }
    return 1;
}

(not sure this even works! dont get mad at me! i havent tested it i only know that it does not give's errors!).