[Nero_3D]

Thats because you create the textdraw each time you call OnPlayerCommandText
The first time it creates and shows it
The second time it creates a new one and hides it (although it was already hidden)
In the end the first one is still beeing shown

Textdraws are generally generated in OnGameModeInit and they use global variables

pawn Код:

// Global
stock
    Text: debugtext
;

pawn Код:

// OnGameModeInit
    debugtext = TextDrawCreate(320.0, 320.0, "debug");

pawn Код:

// OnPlayerCommandText
    if(!strcmp(cmdtext, "/debug", true)) {
        static
            bool: show
        ;
        if((show = !show)) {
            TextDrawShowForPlayer(playerid, debugtext);
            SendClientMessage(playerid, 0xFFFFFFFF, "textdraw on");
        } else {
            TextDrawHideForPlayer(playerid, debugtext);
            SendClientMessage(playerid, 0xFFFFFFFF, "textdraw off");
        }
        return true;
    }