调用ISaveAs2 saveas方法将栅格保存为TIFF格式出现问题

保存为tif后，栅格值范围-3.40282346639e+038到3.40282346639e+038，而且栅格图像未显示 一片空白
代码如下：

pWorkspace = openGisElement.OpenRasterWorkspace(rasterPath) as IWorkspace;
                psaveAs = (ISaveAs2)pGeoDataset;
                psaveAs.SaveAs("temp.tif", pWorkspace, "TIFF");