Issue with saving a flowdocument ,which is using a BlockUIContainer, to RTF file.

Issue: Code is not saving the flowdocument to RTF.

I am using FlowDocumentScrollViewer. Inside this I have a FlowDocument.

In .cs file,  I have a grid.

Grid g = new Grid();

Then Dynamically creating Grid.ColumnDefinitions and RowDefinitions.

Finally adding grid g to  Flowdocument like follows.

flowDocument.Blocks.Add(new BlockUIContainer(g));

This is working fine for previewing and printing using XpsDocumentWriter. 

My problem is with saving this flowDocument to RTF file. I am giving FlowDocumentScrollViewer object and filename to the function like follows.

public static void CreateRTF(FlowDocumentScrollViewer flowDocumentReader, string fileName)
        {
            string copyString = XamlWriter.Save(flowDocumentReader.Document);
            FlowDocument doc = XamlReader.Parse(copyString) as FlowDocument;

            using (FileStream fs = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.Write))
            {
                //TextRange textRange = new TextRange(doc.ContentStart, doc.ContentEnd);
                //textRange.Save(fs, DataFormats.Rtf);
                var content = new TextRange(doc.ContentStart, doc.ContentEnd);

                if (content.CanSave(DataFormats.Rtf))
                {
                    using (var stream = new MemoryStream())
                    {
                        content.Save(stream, DataFormats.Rtf);
                    }
                }
            }

        }

Issue is: When I am running this, I am getting only empty file. 

I appreciate all your helps.

Binu