[SOLVED] How to use the XML API?

Hello!

I want to load a XML scene file in C++,but meet some problems.

here is my project.

#include <sofa/helper/ArgumentParser.h>
#include <SofaSimulationGraph/init.h>
#include <SofaSimulationGraph/DAGSimulation.h>
#include <SofaSimulationCommon/SceneLoaderXML.h>
#include <sofa/simulation/Node.h>
#include <SofaGraphComponent/Gravity.h>
#include <SofaExplicitOdeSolver/EulerSolver.h>
#include <SofaBaseVisual/VisualStyle.h>
#include <sofa/core/objectmodel/Context.h>
#include <SofaBaseCollision/SphereModel.h>
#include <sofa/core/VecId.h>
#include <sofa/gui/GUIManager.h>
#include <sofa/gui/Main.h>

#include <sofa/helper/system/glut.h>
#include <sofa/helper/accessor.h>

#include <SofaComponentCommon/initComponentCommon.h>
#include <SofaComponentBase/initComponentBase.h>
#include <SofaComponentGeneral/initComponentGeneral.h>
#include <SofaComponentAdvanced/initComponentAdvanced.h>
#include <SofaComponentMisc/initComponentMisc.h>

using sofa::component::odesolver::EulerSolver;
using namespace sofa::component::collision;
using sofa::core::objectmodel::Data;
using sofa::helper::ReadAccessor;
using sofa::helper::WriteAccessor;
using sofa::core::VecId;
using sofa::core::objectmodel::New;

//Using double by default, if you have SOFA_FLOAT in use in you sofa-default.cfg, then it will be FLOAT.
#include <sofa/component/typedef/Sofa_typedef.h>
// ---------------------------------------------------------------------
// ---
// ---------------------------------------------------------------------
int main(int argc, char** argv)
{
    glutInit(&argc,argv);
    sofa::simulation::graph::init();
    sofa::component::initComponentBase();
    sofa::component::initComponentCommon();
    sofa::component::initComponentGeneral();
    sofa::component::initComponentAdvanced();
    sofa::component::initComponentMisc();
    sofa::gui::initMain();

    sofa::helper::parse("This is a SOFA application.")
    (argc,argv);

    // The graph root node
    sofa::simulation::setSimulation(new sofa::simulation::graph::DAGSimulation());
	sofa::simulation::Node::SPtr groot =sofa::simulation::SceneLoaderXML().load("D:/workfile/sofa/v16.08/src/share/XMLfile/ball.xml");
 
    sofa::simulation::graph::getSimulation()->init(groot.get());
    groot->setAnimate(false);

    //======================================
    // Set up the GUI
    sofa::gui::GUIManager::Init(argv[0]);
    sofa::gui::GUIManager::createGUI(groot);
    sofa::gui::GUIManager::SetDimension(800,700);
//    sofa::gui::GUIManager::SetFullScreen();  // why does this not work ?

    //=======================================
    // Run the main loop
    sofa::gui::GUIManager::MainLoop(groot);

    sofa::simulation::graph::cleanup();
    return 0;
}

Here is my XML file

<Node>
  <MechanicalObject template="Vec3" position="0 0 0" name="dofs" />
  <UniformMass />
  <FixedConstraint indices="0" />
  <SphereModel radius="0.5" />
</Node>

When I run my project in debug, I found an error at line sofa::gui::GUIManager::createGUI(groot); and the detail display Unhandled exception at 0x000007FED8774362 (SofaGuiQt_d.dll) in XMLLoaderTest.exe: 0xC0000005: Access violation reading location 0x0000000000000000.

Can someone help me?