ERROR 010024: Error during conversion.

//插值点图层
            IFeatureLayer layer = new FeatureLayerClass();
            layer = MainAxMapControl.get_Layer(comboBox1.SelectedIndex) as IFeatureLayer;
            //插值边界图层
            IFeatureLayer pmaskFlayer = new FeatureLayerClass();
            pmaskFlayer = MainAxMapControl.get_Layer(comboBox2.SelectedIndex) as IFeatureLayer;
            //设置插值边界
            IGeoDataset pmaskGeoDB = pmaskFlayer.FeatureClass as IGeoDataset;
            object extend = pmaskGeoDB.Extent;
            object obj = null;
            //设置插值属性
            IFeatureClass featureClass = layer.FeatureClass;
            IFeatureClassDescriptor feades = new FeatureClassDescriptorClass();
            feades.Create(featureClass, null, comboBox3.SelectedItem.ToString());            object dCell = 0.001;//插值精度            IRasterRadius rasterrad = new RasterRadiusClass();
            object Missing = Type.Missing;
            rasterrad.SetVariable(12, ref Missing);
            
            IInterpolationOp pInterpolationOp = new RasterInterpolationOpClass();            //IInterpolationOp3 interpla = new RasterInterpolationOpClass();
            IRasterAnalysisEnvironment rasanaenv = pInterpolationOp as IRasterAnalysisEnvironment;
            rasanaenv.SetCellSize(esriRasterEnvSettingEnum.esriRasterEnvValue, ref dCell);//栅格大小
            rasanaenv.SetExtent(esriRasterEnvSettingEnum.esriRasterEnvValue, ref extend, ref obj);//设置插值边界
            rasanaenv.Mask = pmaskGeoDB;
            //执行插值
            IRaster praster = pInterpolationOp.IDW(feades as IGeoDataset, 2, rasterrad, ref Missing ) as IRaster;执行最后一句时，发生“ERROR 010024: Error during conversion.”错误