[greentarch]

I found this at a_samp

pawn Код:

#define INVALID_3DTEXT_ID                       (0xFFFF)

Maybe you can try to check it like this

pawn Код:

if ( label == INVALID_3DTEXT_ID ) // The label is an invalid one.
{
    SendClientMessage( playerid, -1, "SERVER: That label does not exist!" );
}