OnLButtonDown 没反应。。编译没错

这个例子里面，我这个设置了鼠标单击移动的快慢  而且编译没有错误 为啥这个功能没反应 ？

请大神给我说一下、、、谢谢

// KeyTsetView.cpp : implementation of the CKeyTsetView class
//

#include "stdafx.h"
#include "KeyTset.h"

#include "KeyTsetDoc.h"
#include "KeyTsetView.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

/////////////////////////////////////////////////////////////////////////////
// CKeyTsetView

IMPLEMENT_DYNCREATE(CKeyTsetView, CView)

BEGIN_MESSAGE_MAP(CKeyTsetView, CView)
	//{{AFX_MSG_MAP(CKeyTsetView)
	ON_WM_KEYDOWN()
	ON_WM_LBUTTONDOWN()
	ON_WM_RBUTTONDOWN()
	//}}AFX_MSG_MAP
	// Standard printing commands
	ON_COMMAND(ID_FILE_PRINT, CView::OnFilePrint)
	ON_COMMAND(ID_FILE_PRINT_DIRECT, CView::OnFilePrint)
	ON_COMMAND(ID_FILE_PRINT_PREVIEW, CView::OnFilePrintPreview)
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CKeyTsetView construction/destruction

CKeyTsetView::CKeyTsetView()
{
	// TODO: add construction code here
	m_pt.x=200; 
	m_pt.y=200; 
	step=2;
i=0;
}

CKeyTsetView::~CKeyTsetView()
{
}

BOOL CKeyTsetView::PreCreateWindow(CREATESTRUCT& cs)
{
	// TODO: Modify the Window class or styles here by modifying
	//  the CREATESTRUCT cs

	return CView::PreCreateWindow(cs);
}

/////////////////////////////////////////////////////////////////////////////
// CKeyTsetView drawing

void CKeyTsetView::OnDraw(CDC* pDC)
{
	CKeyTsetDoc* pDoc = GetDocument();
	ASSERT_VALID(pDoc);
	pDC->Ellipse(m_pt.x,m_pt.y,m_pt.x+50,m_pt.y+50); //画圆
	// TODO: add draw code for native data here
}

/////////////////////////////////////////////////////////////////////////////
// CKeyTsetView printing

BOOL CKeyTsetView::OnPreparePrinting(CPrintInfo* pInfo)
{
	// default preparation
	return DoPreparePrinting(pInfo);
}

void CKeyTsetView::OnBeginPrinting(CDC* /*pDC*/, CPrintInfo* /*pInfo*/)
{
	// TODO: add extra initialization before printing
}

void CKeyTsetView::OnEndPrinting(CDC* /*pDC*/, CPrintInfo* /*pInfo*/)
{
	// TODO: add cleanup after printing
}

/////////////////////////////////////////////////////////////////////////////
// CKeyTsetView diagnostics

#ifdef _DEBUG
void CKeyTsetView::AssertValid() const
{
	CView::AssertValid();
}

void CKeyTsetView::Dump(CDumpContext& dc) const
{
	CView::Dump(dc);
}

CKeyTsetDoc* CKeyTsetView::GetDocument() // non-debug version is inline
{
	ASSERT(m_pDocument->IsKindOf(RUNTIME_CLASS(CKeyTsetDoc)));
	return (CKeyTsetDoc*)m_pDocument;
}
#endif //_DEBUG

/////////////////////////////////////////////////////////////////////////////
// CKeyTsetView message handlers

void CKeyTsetView::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags) 
{
	// TODO: Add your message handler code here and/or call default
	if(nChar==VK_LEFT)
	{
		m_pt.x=m_pt.x-step;
		Invalidate();
	}	
	if(nChar==VK_RIGHT)
	{
		m_pt.x=m_pt.x+step;
		Invalidate();
	}	
	if(nChar==VK_DOWN)
	{
		m_pt.y=m_pt.y+step;
		Invalidate();
	}
	if(nChar==VK_UP)
	{
		m_pt.y=m_pt.y-step;
		Invalidate();
	}
	CView::OnKeyDown(nChar, nRepCnt, nFlags);
}

void CKeyTsetView::OnLButtonDown(UINT nFlags, CPoint point) 
{
	// TODO: Add your message handler code here and/or call default
	//radius=radius+5;
	step=step+2;
	Invalidate();
	i++;
	if(i==1)
	
	{
		m_pt11=m_pt12=point;

	}
	else{
	CClientDC dc(this);
	dc.MoveTo(m_pt11);
	dc.LineTo(point);
	m_pt11=point;
	}
	CView::OnLButtonDown(nFlags, point);
}

void CKeyTsetView::OnRButtonDown(UINT nFlags, CPoint point) 
{
	// TODO: Add your message handler code here and/or call default
		CClientDC dc(this);
dc.MoveTo(m_pt11);
	dc.LineTo(m_pt12);
	i=0;
	CView::OnRButtonDown(nFlags, point);
}

Invalidate();调用后，无论你在LButtonDown函数里画了什么，在函数退出后都会自动调用OnDraw清除背景然后画圆