Game Engine

I’m new to the board but I’m no flash newbie. Anyway, I was hoping someone could help me out because this is really annoying. I’m making a Zelda (NES) type game and most of it is going smoothly, but there is one problem. There is an item, the Bow and Arrow, and that is a movie clip. Inside the MC there is a text field to display the amount of arrows you have. I have the actions set to where everytime you hit a key, it subtracts an arrow and fires it. NOW, all I want, is when the text field reaches the number ‘0’, to stop firing upon keypress and disable the Bow and Arrow item. Any help would be greatly appreciated. Attached is the .fla. Thank you so much!