how to write argotic.feed.save result into memory stream?

I want to write Argotic to memorystream and then return it as a string to another function.and this is what I've written :

            Stream st = new MemoryStream();            Feed.Save(st); //argotic Save method has the ability to write into Stream            StreamReader sr = new StreamReader(st);            return sr.ReadToEnd();

but I only got an empty string although the st.length shows me the correct length but there no character in it :-?

how Can I solve this problem?

regards.