有关AE中获取拓扑层的问题

<P>做了一个关于拓扑编辑的操作，参考的是<a href="http://bbs.gissky.net/blog.asp?id=118" target="_blank" >http://bbs.gissky.net/blog.asp?id=118</A></P>
<P>但是在获取topoLayer 时候发现，不能将打开的GDB中的ilayer直接赋给它。</P>
<P>我觉得可能是没有建立拓扑的原因，后来按照AE帮助里ITopologyContainer接口的CreateTopology方法中的Example获取拓扑图</P>
<P>Dim pWSFact As IWorkspaceFactory<BR>Set pWSFact = New AccessWorkspaceFactory</P>
<P>Dim pWor As IWorkspace<BR>Set pWor = pWSFact.OpenFromFile("D:\MyTopology.mdb", 0)</P>
<P>Dim pFWS As IFeatureWorkspace<BR>Set pFWS = pWor</P>
<P>Dim pDS As IDataset<BR>Set pDS = pFWS.OpenFeatureDataset("MyFD")</P>
<P>Dim pTopoCont As ITopologyContainer<BR>Set pTopoCont = pDS</P>
<P>'Create the topology<BR>Dim pTopo As ITopology<BR><FONT color=#f70938>Set pTopo = pTopoCont.CreateTopology("Topo", pTopoCont.DefaultClusterTolerance, -1, "")</FONT></P>
<P>Dim pFCC As IFeatureClassContainer<BR>Set pFCC = pDS</P>
<P>Dim pFC As IFeatureClass<BR>Set pFC = pFCC.ClassByName("Roads")</P>
<P>'Add the feature class to the topology<BR>pTopo.AddClass pFC, 5, 1, 1, False</P>
<P>但是在运行到红色那句时候，却执行不通过，错误提示是：“这个集合中找不到此项目”</P>

<P>哪位做的指点下，谢谢了。</P>