[Konstantinos]

That's why the case parameter is set to true so "setusa", "SETUSA" are the same. id will always be 0 and string 250? The message is not even 60 lenght.

pawn Код:

if (!strcmp("/setusa", cmdtext, true, 7))
{
    if (!IsPlayerAdmin(playerid)) return 1;

    new
        id = strval(cmdtext[8]);
    
    if (!IsPlayerConnected(id)) return SendClientMessage(playerid, COLOR_RED, "Invalid Player");

    SetPlayerTeam(id, 0);
    SetPlayerColor(id, COLOR_BLUETEAM);
    gTeam[id] = TEAM_USA;

    new
        pname1[MAX_PLAYER_NAME], 
        string[58];
    
    GetPlayerName(id, pname1, MAX_PLAYER_NAME);
    format(string, sizeof (string), "You Set %s (%d) Team To {0x0000FF}USA", pname1, id);
    return 1;
}

If it displays the unknown message again after using the above code, load crashdetect plugin.