[ViruZZzZ_ChiLLL]

Well if your using :

dcmd & strcmp:

pawn Код:

public OnPlayerCommandText(playerid, cmdtext[])
{
   // codes here
   return SendClientMessage(playerid, color, "ERROR : Blah blah blah");
}

Not quite sure with zcmd though :

pawn Код:

CMD:command(playerid, params[])
{
   // code here
   return SendClientMessage(playerid, Color, "ERROR : Blah blah blah");
}

EDIT : LMAO, sorry -.-