Hello everyone, I solved my own question. I'm posting this here so that anyone facing this issue can get some idea.
There is a good reference here on how to read binary data from the AsyncFileUpload Control...http://forums.asp.net/t/1520272.aspx/1
All i needed to do was to assign the stream obj with the FileContent of the Async control...like
myStream = AsyncFileUpload1.FileContent;
myStream.Position = 0;
System.IO.BinaryReader br = new System.IO.BinaryReader(myStream);
byte bytImageBytes = br.ReadBytes((int)myStream.Length);
and set the starting position of the stream to 0 and use a binary reader to read the binary values int a byte array.
I still haven't figured out why my initial code did not work??....i.e the inputstream of the async control....Please, share if you know the reason why.