单值专题图总是一种颜色

我在做单值专题图时，明明已经为Renderer设置了不同的颜色，但是结果却总是一种颜色。代码如下：<br>
<br>
            //打开影响场要素类<br>
            IFeatureClass pFcYxc = pFeatureWorkspace.OpenFeatureClass("YXC");<br>
            //打开影响场图层<br>
            IFeatureLayer pFl = (IFeatureLayer)axMapControl1.Map.get_Layer(1);<br>
<br>
            //创建并设置随机色谱<br>
            IRandomColorRamp rx = new RandomColorRampClass();<br>
            rx.MinSaturation = 15;<br>
            rx.MaxSaturation = 30;<br>
            rx.MinValue = 85;<br>
            rx.MaxValue = 100;<br>
            rx.StartHue = 0;<br>
            rx.EndHue = 360;<br>
            rx.UseSeed = true;<br>
            rx.Seed = 43;<br>
<br>
            //创建填充符号<br>
            ISimpleFillSymbol symx = new SimpleFillSymbolClass();<br>
<br>
            //单值专题图<br>
            IUniqueValueRenderer pRender = new UniqueValueRendererClass();<br>
            pRender.FieldCount = 1;<br>
            pRender.set_Field(0, "LD");<br>
            pRender.DefaultSymbol = (ISymbol)symx;<br>
            pRender.UseDefaultSymbol = true;<br>
<br>
            //为每个值设置一个符号<br>
            int n = pFcYxc.FeatureCount(null);<br>
            IFeatureCursor pFCur = pFcYxc.Search(null, false);<br>
            for (int i = 0; i < n; i++)<br>
            {<br>
                IFeature pFeat = pFCur.NextFeature();<br>
                string pFeatValue = pFeat.get_Value(pFeat.Fields.FindField("LD")).ToString();<br>
                pRender.AddValue(pFeatValue, "烈度", (ISymbol)symx);<br>
            }<br>
<br>
            rx.Size = pRender.ValueCount;<br>
            bool ok = true;<br>
            rx.CreateRamp(out ok);<br>
            IEnumColors RColors = rx.Colors;<br>
            RColors.Reset();<br>
<br>
            //为每个符号设置颜色<br>
            for (int i = 0; i <= pRender.ValueCount - 1; i++)<br>
            {<br>
                string xv = pRender.get_Value(i);<br>
                if (xv != "")<br>
                {<br>
                    ISimpleFillSymbol jsy = (ISimpleFillSymbol)pRender.get_Symbol(xv);<br>
                    jsy.Color = RColors.Next();<br>
                    pRender.set_Symbol(xv, (ISymbol)jsy); <br>
                        //---------------------------------------------------------------------------<br>
                        //在这里设置断点，每一轮循环中jsy.Color的值不相同。<br>
                        //---------------------------------------------------------------------------<br>
                }<br>
            }<br>
<br>
            //设置到图层<br>
            IGeoFeatureLayer pGeoFl = (IGeoFeatureLayer)pFl;<br>
            pGeoFl.Renderer = (IFeatureRenderer)pRender;<br>
            pGeoFl.DisplayField = "LD";<br>
<br>
            //刷新<br>
            axMapControl1.Refresh(esriViewDrawPhase.esriViewGraphics, axMapControl1.Map.get_Layer(1), Type.Missing);<br>
            axMapControl1.Refresh();<br>
            axTOCControl1.Update();

<PRE>Sub MyUVR(theField As String)
'assistance from Michael Knight, from ESRI developers network forum.

    Dim pMxDoc As IMxDocument
    Set pMxDoc = Application.Document
    
    Dim pMap As IMap
    Set pMap = pMxDoc.FocusMap
    
    'create renderer
    Dim pUVR As IUniqueValueRenderer
    Set pUVR = New UniqueValueRenderer

    pUVR.FieldCount = 1
    pUVR.Field(0) = theField '"Code"
    pUVR.DefaultLabel = "No Value"
    
    'create default symbol
    Dim color As IColor
    Set color = CreateColor(255, 255, 0)
    
    Dim defaultMarker As ISimpleMarkerSymbol
    Set defaultMarker = CreateSimpleMarkerSymbol(color, esriSMSSquare, 10)
    
    'add default symbol to renderer
    pUVR.DefaultSymbol = defaultMarker
    pUVR.UseDefaultSymbol = True
    
    
    Dim pStyleStorage As IStyleGalleryStorage
    Dim pStyleGallery As IStyleGallery
    Dim pStyleClass As IStyleGalleryClass
    Set pStyleGallery = pMxDoc.StyleGallery
    Set pStyleStorage = pStyleGallery
    
    Dim pEnumStyleGall As IEnumStyleGalleryItem
    Dim pStyleItem As IStyleGalleryItem
    Dim pMarkerSym As IMarkerSymbol
    
    'Initialize the style gallery
    Set pEnumStyleGall = pStyleGallery.Items("Marker Symbols", "Business.style", "Default")
    pEnumStyleGall.Reset
    Set pStyleItem = pEnumStyleGall.Next
  
  
'I had to had the symbols in this order, which is the order they appear in the
'style page.
'If I tried to add them in a different order, they wouldn't all get added.
'Maybe this has something to do with reseting the symbol gallery?
'I couldn't figure it out, but this works for me.

'symbol 1 - up arrow
    Do While Not pStyleItem Is Nothing   'Loop through and access each marker
       If pStyleItem.Name = "Arrow Up" Then
          Set pMarkerSym = pStyleItem.Item
          pMarkerSym.color = CreateColor(255, 0, 0)
          Exit Do
      End If
      Set pStyleItem = pEnumStyleGall.Next
    Loop
    
    Dim symbol As IMarkerSymbol
    Set symbol = pMarkerSym
    
    pUVR.AddValue "3", "Rising", symbol



'symbol 2 - down arrow, green

    Do While Not pStyleItem Is Nothing   'Loop through and access each marker
       If pStyleItem.Name = "Arrow Down" Then
          Set pMarkerSym = pStyleItem.Item
          pMarkerSym.color = CreateColor(0, 255, 0)
          Exit Do
      End If
      Set pStyleItem = pEnumStyleGall.Next
    Loop

    Set symbol = pMarkerSym
    
    pUVR.AddValue "1", "Falling", symbol


'symbol 3 - right arrow, black

    Do While Not pStyleItem Is Nothing   'Loop through and access each marker
       If pStyleItem.Name = "Arrow Right" Then
          Set pMarkerSym = pStyleItem.Item
          pMarkerSym.color = CreateColor(0, 0, 0)
          Exit Do
      End If
      Set pStyleItem = pEnumStyleGall.Next
    Loop

    Set symbol = pMarkerSym
    
    pUVR.AddValue "2", "Neutral", symbol


'add renderer to layer

    Dim pLayer As ILayer
    'Set pLayer = pMap.Layer(0)
    Set pLayer = GetLayerByName(pMxDoc, "FF_WLCh") 'pMxDoc.FocusMap.Layer(0)
    
    Dim pGeoFeatureLayer As IGeoFeatureLayer
    Set pGeoFeatureLayer = pLayer
    Set pGeoFeatureLayer.Renderer = pUVR
    
    'This makes the layer properties symbology tab show
    'show the correct interface.
    Dim hx As IRendererPropertyPage
    Set hx = New UniqueValuePropertyPage
    pGeoFeatureLayer.RendererPropertyPageClassID = hx.ClassID

    'Refresh the TOC
    pMxDoc.ActiveView.ContentsChanged
    pMxDoc.UpdateContents

    'Draw the map
    pMxDoc.ActiveView.Refresh


End Sub
</PRE>