vb+mapx打印的问题？高手指教

<P>我用的这个函数代码是从例子里帖到我的程序里的，只不过我用的是单文档窗口，例子是多文档窗口。例子打印没有问题。我打印就报地址错误。为什么？请高手指点！</P>
<P>以下是我的打印函数：</P>
<P>void CAppClientView::OnPrint(CDC* pDC, CPrintInfo* pInfo) <BR>{<BR> try {<BR>  double dPaperWidth;<BR>  double dPaperHeight;<BR>    CPoint ptVpOrg;<BR>  CSize szVExt;</P>
<P>  // get paper width in cm and convert to HIMETRIC (100th of a mm)<BR>  m_ctrlMapX.SetPaperUnit(miUnitCentimeter);<BR>  dPaperWidth = m_ctrlMapX.GetMapPaperWidth() * 10 * 100;<BR>  dPaperHeight = m_ctrlMapX.GetMapPaperHeight()* 10 * 100;</P>
<P>  ::GetViewportOrgEx(pDC->m_hDC, ;ptVpOrg);<BR>  ptVpOrg.x = (long)((double)ptVpOrg.x/96.0 * 2540.0);<BR>  ptVpOrg.y = (long)((double)ptVpOrg.y/96.0 * 2540.0);</P>
<P>  if (pInfo->m_bPreview) {<BR>   // now get our drawing width in himetric<BR>   // during print preview the ViewportExtent has this<BR>   ::GetViewportExtEx(pDC->m_hDC, ;szVExt);<BR>   pDC->DPtoHIMETRIC(;szVExt);<BR>   // also, keep the aspect ration of the map so it isn't distorted<BR>   szVExt.cy = (long)((double)szVExt.cy * (dPaperHeight/dPaperWidth));<BR>   m_ctrlMapX.PrintMap((long)pDC->m_hDC, ptVpOrg.x, ptVpOrg.y, szVExt.cx, szVExt.cy);<BR>  }<BR>  else {<BR>   m_ctrlMapX.PrintMap((long)pDC->m_hDC, ptVpOrg.x, ptVpOrg.y, (long)dPaperWidth, (long)dPaperHeight);<BR>  }<BR> }<BR> catch (COleDispatchException *e) {<BR>  e->ReportError();<BR>  e->Delete();<BR> }<BR> catch (COleException *e) {<BR>  e->ReportError();<BR>  e->Delete();<BR> }<BR> CView::OnPrint(pDC, pInfo);<BR>}</P>

对不起，是vc+mapx,