Slideshow, movieclip and this.stop();

In a slideshow I made. I have on main four movieclips with several between rooms and these have added this.stop(); And in one of the movieclip inside it has put there several times this.stop(); but when I go back with a button exportroot button and then to go back to movieclip with several stops it doesn't play but when I remove many this.stop(); then it works and I have one stop and then it works. Why is that for?