[Jonny5]

you cannot use SendClientMessage to format a string
and im not sure why you would use SendClientMessageEx at all in this case

you must format a string first then use it in sendclientmessage

kinda like this

pawn Код:

CMD:a(playerid, params[])
{
     if(PlayerData[playerid][AdminLevel] < 1) return SendClientMessage(playerid,COLOR_RED,"You need to be an administrator to use this command!");
     new text[128],strOut[128];
     if(sscanf(params,"s[128]",text)) return SendClientMessage(playerid,COLOR_RED,"-USAGE- /a [text]");
     for(new i = 0;i<MAX_PLAYERS;i++)
    {
        if(!IsPlayerConnected(i)) continue;
        if(PlayerData[playerid][AdminLevel] < 1) continue;
        format(strOut,sizeof(strOut),"%s%s%s%s","Adminchat: ",PlayerInfo[playerid][Username],": {FFFFFF}",text);
        SendClientMessage(i,color_yellow,strOut);
    }
    return 1;
}