Üdv!
Itt az a hiba ,hogy a case után karaktereket írtam, nem pedig számot?
[pawn]stock IsPlayerFDAdmin(playerid)
{
     new adminname[MAX_PLAYER_NAME];
     GetPlayerName(playerid, adminname, MAX_PLAYER_NAME);
     switch(adminname)
     {
          case [FD_GangSteR]: PlayerInfo[playerid][Level] = 3;
          case [FD]Matyi10012, Matyi10012: PlayerInfo[playerid][Level] = 3;
          case [FD]Henk_Moody: PlayerInfo[playerid][Level] = 2;
          case [FD]Pedro: PlayerInfo[playerid][Level] = 2;
          case [FD]Fuesko: PlayerInfo[playerid][Level] = 2;
          case [FD]Deserteer: PlayerInfo[playerid][Level] = 2;
          case [FD]staR, staR: PlayerInfo[playerid][Level] = 2;
          case [FD]twido: PlayerInfo[playerid][Level] = 2;
          case [FD]Zombie_Hunter, [FD]Zombie_hunter, [FD]Zombi_hunter: PlayerInfo[playerid][Level] = 2;
          case [FD]relativ: PlayerInfo[playerid][Level] = 2;
          case [FD]Jack_Lock: PlayerInfo[playerid][Level] = 2;
          case [FD]Anderson: PlayerInfo[playerid][Level] = 2;
     }
}[/pawn]

Próbáld meg így:
 

stock IsPlayerFDAdmin(playerid)
{
     new adminname[MAX_PLAYER_NAME];
     GetPlayerName(playerid, adminname, MAX_PLAYER_NAME);
     if(strcmp(adminname, \"[FD_GangSteR]\", 0) == 0) PlayerInfo[playerid][Level] = 3;
     // Ide meg a többit...
}

Rosszul használod a case-t...
Használat:
[pawn]case [FD_GangSteR]: { PlayerInfo[playerid][Level] = 3; }[/pawn]
Ezt ne hagyd ki.
 

{ }
 

Ha egy soros nem kell az {} jel.