How do you know the High Score is staying at 0?
I don't see anyplace you are updating the high score text with the high score. Does that make sense?
On start of layout you are setting the text of the HighScore text object to varHighscore.
But you never update the text box if the highscore is beaten. So it's always showing whatever the high score was when you start the game.
<img src="http://content.screencast.com/users/ArcadEd/folders/Jing/media/786d58ad-4a14-46a2-b2f8-1a5df91e2f1f/2013-05-28_1634.png" border="0" />