请问这样遍历AcDb3dPolyline的节点有问题吗？

Gambler

..............

if (strcmp(pCname, "AcDb3dPolyline")==0)
  {
   AcDb3dPolyline *pLine;
   pLine = AcDb3dPolyline::cast(pEntity);

   AcDbObjectIterator* pverIetor;
   pverIetor = pLine->vertexIterator();
   pLine->close();
   
   AcDb2dVertex *pVertex;
   AcGePoint3d pt;
   AcDbObjectId vertexObjId;

   for(pverIetor->start(); !pverIetor->done(); pverIetor->step())
   {
    vertexObjId = pverIetor->objectId();
    acdbOpenObject(pVertex, vertexObjId, AcDb::kForRead);

   ///    ////////////////////  
    // pVertex->close();
      }
  }

为什么这段代码在红色处运行出错？

请问这样遍历AcDb3dPolyline的节点有问题吗？