[DanishHaq]

pawn Код:

public OnPlayerConnect(playerid)
{
    TextDrawShowForPlayer(playerid, TD1);
    if(fexist(UserPath(playerid)))
    {
        INI_ParseFile(UserPath(playerid), "LoadUser_%s", .bExtra = true, .extra = playerid);
        ShowPlayerDialog(playerid, DIALOG_LOGIN, DIALOG_STYLE_INPUT, "{FFFFFF}Login", "{FFFFFF}Type your PASSWORD to login!", "Login", "Quit");
    }
    else
    {
        ShowPlayerDialog(playerid, DIALOG_REGISTER, DIALOG_STYLE_INPUT, "{FFFFFF}Register", "{FFFFFF}Type your PASSWORD to register!", "Register", "Quit");
    }
    return 1;
}

Try that. Re-writ your code a little.

Note: You had a few errors in here too, I didn't see your UserPath, check the post below for that.