Pretty neat animation you have there (I would recommend rendering it at 1:1 pixel size, though, your game will take forever to load with these detailed animations at twice the size or more).
Anyhow - took me a while to get through your events, but here's what's up:
<img src="http://images.devs-on.net/Image/YTQO6n2BGncvmIG-Screen1.png" border="0" />
The bullet behaviour wasn't giving it an angle so any angle-based events weren't happening. And then you'd have to check the angle and flip as necessary. Just do the same events as shown in the image and it should be ok.