Action script problem on alpha (flash 8) pls help guyz

I am doing an alpha transition (alpha 0% - 100%)in Flash 8… Here’s my code:

this._alpha = 0;

this._alpha += 5;

if(this._alpha >=100){


When I run the movie, it works but after a few seconds or minutes, the object on stage disappeared… And that’s my problem… Even I used stop command, the problem is still the same… The object still disappearing… Is there anything wrong with my script?? Im juz a beginner… Plz help guyz… tnx in advance :h::h: