ArcgisEngine中CAD要素导入SDE，程序报错

/// <summary>
        /// 将CAD中的要素类复制到sde空间
        /// </summary>
        public void ConvertCADToSDE()
        {
            // Create a name object for the source (fileGDB) workspace and open it.
            IWorkspaceName sourceWorkspaceName = getWorkspaceName("esriDataSourcesFile.CadWorkspaceFactory", cadFilePath);

            IName sourceWorkspaceIName = (IName)sourceWorkspaceName;
            IWorkspace sourceWorkspace = (IWorkspace)sourceWorkspaceIName.Open();

            // Create a name object for the target (SDE) workspace and open it.
            IWorkspaceName targetWorkspaceName = getWorkspaceName("esriDataSourcesGDB.SdeWorkspaceFactory", sdePath);
            IName targetWorkspaceIName = (IName)targetWorkspaceName;
            IWorkspace targetWorkspace = (IWorkspace)targetWorkspaceIName.Open();

            // Create a name object for the source dataset.
            IFeatureClassName sourceFeatureClassName = getFeatureClassName(sourceWorkspaceName, sourceFCName);

            // Create a name object for the target dataset.
            IFeatureClassName targetFeatureClassName = getFeatureClassName(targetWorkspaceName, targetFCName);

            // Open source feature class to get field definitions.
            IName sourceName = (IName)sourceFeatureClassName;
            IFeatureClass sourceFeatureClass = (IFeatureClass)sourceName.Open();

            // Create the objects and references necessary for field validation.
            IFieldChecker fieldChecker = new FieldCheckerClass();
            IFields sourceFields = sourceFeatureClass.Fields;
            IFields targetFields = null;
            IEnumFieldError enumFieldError = null;

            // Set the required properties for the IFieldChecker interface.
            fieldChecker.InputWorkspace = sourceWorkspace;
            fieldChecker.ValidateWorkspace = targetWorkspace;

            // Validate the fields and check for errors.
            fieldChecker.Validate(sourceFields, out enumFieldError, out targetFields);
            if (enumFieldError != null)
            {
                // Handle the errors in a way appropriate to your application.
                Console.WriteLine("Errors were encountered during field validation.");
            }

            // Find the shape field.
            String shapeFieldName = sourceFeatureClass.ShapeFieldName;
            int shapeFieldIndex = sourceFeatureClass.FindField(shapeFieldName);
            IField shapeField = sourceFields.get_Field(shapeFieldIndex);

            // Get the geometry definition from the shape field and clone it.
            IGeometryDef geometryDef = shapeField.GeometryDef;
            IClone geometryDefClone = (IClone)geometryDef;
            IClone targetGeometryDefClone = geometryDefClone.Clone();
            IGeometryDef targetGeometryDef = (IGeometryDef)targetGeometryDefClone;

            // Cast the IGeometryDef to the IGeometryDefEdit interface.
            IGeometryDefEdit targetGeometryDefEdit = (IGeometryDefEdit)targetGeometryDef;

            // Set the IGeometryDefEdit properties.
            //targetGeometryDefEdit.GridCount_2 = 1;
            //targetGeometryDefEdit.set_GridSize(0, 0.75);

            // Create a query filter to only select features you want to convert
            IQueryFilter queryFilter = new QueryFilterClass();

            // Create the converter and run the conversion.
            IFeatureDataConverter featureDataConverter = new FeatureDataConverterClass();
            IEnumInvalidObject enumInvalidObject = featureDataConverter.ConvertFeatureClass
                (sourceFeatureClassName, queryFilter, null, targetFeatureClassName,
                targetGeometryDef, targetFields, "", 1000, 0);

            // Check for errors.
            IInvalidObjectInfo invalidObjectInfo = null;
            enumInvalidObject.Reset();
            while ((invalidObjectInfo = enumInvalidObject.Next()) != null)
            {
                // Handle the errors in a way appropriate to the application.
                Console.WriteLine("Errors occurred for the following feature: {0}",
                    invalidObjectInfo.InvalidObjectID);
            }
        }