Program crashes after running for a few seconds/mins--issue with push_back()

Hi

I'm drawing lines between two markers in osgart. So whenever they are moved, the lines are updated each time.

For this I'm updating an 
Code:
osg::ref_ptr<osg::Vec3Array> points

My program crashes after it is run for a several seconds/minutes. I found out that the following lines cause
the issue (commenting those can avoid it)

Code:
points->push_back(StartPoint); 
points->push_back(EndPoint);

I assume it is due to a memory leak, eventhough I use points->clear() at the end.

Here's my code (please note that some lines have been omitted for clarity)

Code:
class CallBackClass: public osg::NodeCallback{

private:
	osg::ref_ptr<osg::Vec3Array> points; 
	osg::ref_ptr<osg::Geometry> beam; 

public:
	CallBackClass::CallBackClass(){
		points = new osg::Vec3Array; 
		beam = new osg::Geometry; 
	}

	void CallBackClass::operator(){
		//	osg::Vec3   StartPoint,
		// osg::Vec3   EndPoint

		points->push_back(StartPoint); 
		points->push_back(EndPoint);
		beam->setVertexArray(points.get()); 
		beam->setColorArray(color.get()); 
		beam->setColorBinding(osg::Geometry::BIND_PER_PRIMITIVE); 
		beam->addPrimitiveSet(new osg::DrawArrays(GL_LINES,0,2));
                points->clear();
	}
}

Thanks in advance.

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