OSG AutoTransform problem

#include <osg/MatrixTransform>
#include <osg/Texture2D>
#include <osg/Geode>
#include <osg/AutoTransform>

#include <osgDB/ReadFile>

#include <osgViewer/Viewer>

int main(int argc, char **argv)
{
    osg::AutoTransform *at = new osg::AutoTransform;
    at->setAutoScaleToScreen(true);
    at->setAutoRotateMode( osg::AutoTransform::ROTATE_TO_SCREEN );

    osg::Vec3Array* verts = new osg::Vec3Array(4);
    (*verts)[0] = osg::Vec3(-4.0f,  0.0f, 0.0f);
    (*verts)[1] = osg::Vec3( 4.0f,  0.0f, 0.0f);
    (*verts)[2] = osg::Vec3( 0.0f,  4.0f, 0.0f);
    (*verts)[3] = osg::Vec3( 0.0f, -4.0f, 0.0f);

    osg::Vec4Array* colors = new osg::Vec4Array(1);
    (*colors)[0].set(0, 1, 1, 1);

    osg::Geometry* geometry = new osg::Geometry;
    geometry->setVertexArray( verts );
    geometry->setColorArray( colors );
    geometry->setColorBinding( osg::Geometry::BIND_OVERALL );
    geometry->addPrimitiveSet( new osg::DrawArrays(GL_LINES, 0, 4));

    osg::Geode* geode = new osg::Geode;
    geode->addDrawable(geometry);

    at->addChild(geode);

    osgViewer::Viewer viewer;
    viewer.setUpViewInWindow(0, 0, 640, 480);
    viewer.setSceneData(at);

    return viewer.run();
}