[Darnell]

PHP код:

forward OnPlayerCommandPerformed(playerid, cmdtext[], success); 
public OnPlayerCommandPerformed(playerid, cmdtext[], success) 
{ 
    if(!success) SendClientMessage(playerid, COLOR, "You have entered a invalid command."); 
    return 1; 
} 


Try that, won't think it'll help, check if there's return 0; in the end of OnPlayerCommandText if you use strcmp.