public OnPlayerText(playerid, text[]) 
{
    if(PlayerInfo[playerid][pAdmin] > 0 && text[0] == '#') 
    {
         new message[128], pName[MAX_PLAYER_NAME];
         GetPlayerName(playerid, pName, MAX_PLAYER_NAME);
         format(message, sizeof(message), "Admin Chat: %s: %s", pName, text[1]);
         for(new i = 0, i < MAX_PLAYERS, i++) 
         {
             if(PlayerInfo[playerid][pAdmin] > 0 && IsPlayerConnected(i))
             {
                  SendClientMessage(i, -1, text);
             } 
         }
    }
    return 1;
}

public OnPlayerText(playerid, text[])
{
    if(text[0] == '#' && PlayerInfo[playerid][pAdmin])
    {
        new str[128], name[MAX_PLAYER_NAME];
        GetPlayerName(playerid, name, sizeof(name));
        format(str, sizeof(str), "(ADMIN CHAT) %s: {FFFFFF}%s", name, text[1]);
        //If you have a SendAdminMessage or something, use it here instead of the loop
        for(new i = 0; i < MAX_PLAYERS; i++) //foreach is better :)
        {
            if(!IsPlayerConnected(i)) continue;
            if(!PlayerInfo[playerid][pAdmin]) continue;
            SendClientMessage(i, -1, str); //'-1' is the color, change that to whatever you want your admin chat to be
        }
        return 0;
    }
    return 1;
}

CMD:achat(playerid,params[])
{
if(IsPlayerAdmin(playerid))
{
new str[144];
if(sscanf(params,"s[144]",str))
  {
     SendClientMessage(playerid,-1,"/achat [text]");
     return 1;
   }
else
   {
      new str1[128];
      new name[128];
      GetPlayerName(playerid,name,sizeof(name));
      format(str1,sizeof(str1),"*Admin %s:%s",name,str);
      SendClientMessageToAll(-1,str1);
    }
}
else
{
SendClientMessage(playerid,-1,"You are not an Admin");
return 1;
}
return1;
}