1.Pentru comenzi obisnuite(OnPlayerCommandText)
Mergeti la functia OnPlayerCommandText si coborati pana unde este return 0; si adaugati,inainte de return 0, asta:

Cod:

else
{
new Str[256];
format(Str,256,"EROARE:Comanda {204096}%s{962020} nu exista!Incercati /help si /cmds",cmdtext);
SendClientMessage(playerid,0x962020,Str);
return 1;
}

Apoi stergi return 0; si dai compile.
ex:

Cod:

public OnPlayerCommandText(playerid,cmdtext[])
{
    if(strcmp(cmdtext,"/test")==0)
    {
        SendClientMessage(playerid,~0,"-");
        return 1;
    }
    //si alte sute de comenzi.
    else
    {
    new Str[256];
    format(Str,256,"EROARE:Comanda {204096}%s{962020} nu exista!Incercati /help si /cmds",cmdtext);
    SendClientMessage(playerid,0x962020,Str);
    return 1;
    }
}

2.Pentru ZCMD
Cautati in mod functia OnPlayerCommandPerformed. DACA o gasiti,adaugati asta:

Cod:

if(!success)
{
    new Str[256];
    format(Str,256,"EROARE:Comanda {204096}%s{962020} nu exista!Incercati /help si /cmds",cmdtext);
    SendClientMessage(playerid,0x962020,Str);
    return 1;
}

Daca nu o gasiti,inafara oricarei functii(de preferat...dupa OnPlayerSpawn-e o functie care o gasesti in mai toate modurile)pui asta:

Cod:

public OnPlayerCommandPerformed(playerid, cmdtext[], success)
{
    if(!success)
    {
        new Str[256];
        format(Str,256,"EROARE:Comanda {204096}%s{962020} nu exista!Incercati /help si /cmds",cmdtext);
        SendClientMessage(playerid,0x962020,Str);
    }
    return 1;
}