请大侠帮忙，专题图做不出来？？？

<P>调试发现只要运行到Refresh函数刷新的时候就出错，程序异常关闭</P>
<P>小弟请教各位大侠，帮忙看看，不胜感激！！！</P>
<P>代码如下：</P>
<P> IChartRendererPtr pRender(CLSID_ChartRenderer);</P>
<P> pRender->put_Label(fn);</P>
<P> IRendererFieldsPtr pRenderFields = pRender;<BR> BSTR fn = COleVariant(m_Fn).bstrVal;<BR> pRenderFields->AddField(fn, fn);</P>
<P> IBarChartSymbolPtr pBarSym(CLSID_BarChartSymbol);<BR> pBarSym->put_VerticalBars(true);<BR> pBarSym->put_Width(6);<BR> pBarSym->put_Spacing(0);</P>
<P> IChartSymbolPtr pChartSym = pBarSym;<BR> pChartSym->put_MaxValue(10);</P>
<P> IMarkerSymbolPtr pMarkSym = pBarSym;<BR> pMarkSym->put_Size(16);</P>
<P> ISimpleFillSymbolPtr pFillSymBase(CLSID_SimpleFillSymbol);<BR> IColorPtr pColor(CLSID_RgbColor);<BR> pColor->put_RGB(RGB(50, 250, 100));<BR> pFillSymBase->put_Color(pColor);</P>
<P> ISimpleFillSymbolPtr pFillSym(CLSID_SimpleFillSymbol);<BR> pColor->put_RGB(RGB(50, 250, 100));<BR> pFillSym->put_Color(pColor);</P>
<P> ISymbolPtr pSym = pFillSym;<BR> ISymbolArrayPtr pSymArray = pRender;<BR> pSymArray->AddSymbol(pSym);</P>
<P> pSym = pFillSymBase;<BR> pRender->putref_BaseSymbol(pSym);</P>
<P> pRender->putref_ChartSymbol(pChartSym);</P>
<P> IFeatureRendererPtr pRen = pRender;</P>
<P> pGeoLayer->putref_Renderer(pRen);<BR> MapPtr->m_map.Refresh(esriViewGeography, vtMissing, vtMissing);</P>
<P><BR> CDialog::OnOK()</P>
<P>调试发现只要运行到Refresh函数刷新的时候就出错，程序异常关闭</P>
<P>小弟请教各位大侠，帮忙看看，不胜感激！！！</P>

<P>在arcgis9.1的开发包里有个ArcGIS\DeveloperKit\samples\Cartography\Display_RenderersVisual_Basic</P>
<P>例子，演示了各种专题图的制作</P>
<P>9.0版本应该有的，你找找</P>

我就是按照那个作的