ofxBox2d destroyShape() error on VC++

Hi all,

I’m an oF newbie and trying to generate particles interaction with ofxBox2d.

I could generate hundreds of ofxBox2dCircles and display them.
But when I delete some ofxBox2dCircles with destroyShape(),
unhandled exception occured.
I doubted other reasons about the problem and put many breakpoints,
problems are always occured when calling destroyShape().
(Debugger was stopped inside b2Shape::DestroyProxy() of b2Shape.cpp.)
Of course my ofxBox2dCircles had valid circle objects.

Excerpt of my codes are below.

ofxBox2dCircle c = ofxBox2dCircle();  
c.setPhysics(2, 0.8, 2);  
c.setup(box2d.getWorld(), x, y, ofRandom(3, 14));  
box2dCircles.at(0).destroyShape(); // unhandled exception  

I’m using Windows 7, Visual Studio 2010, oF0072, and ofxBox2d 2.2.
Any advices are welcome.