DocumenContext fails

Hi,
I am trying to capture the contents of a mail. SO I have created an agent(shared agent) (After new mail has arrived).
But after debugging I have found that :
     Set doc = session.DocumentContext
     Ifrom = doc.from(0) ----> fails ??? Any reason
I have tried an alternate ways bu still fails :
Set it = doc.GetFirstItem("Subject")
but it also fails.
Here is the detail code :
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Sub Initialize
     Dim session As NotesSession
     Set session = New NotesSession
     Dim db As NotesDatabase
     Dim doc As NotesDocument
     Dim dbug As NotesLog
     Dim rtitem As Variant
     Dim fileCount As Integer
     Dim it As NotesItem
     Dim user As String
'     REM get the incoming mail message
     Set doc = session.documentcontext
'REM Specify the size limit for attachments
     Const MaxSize = 0
     fileCount = 0
     Set dbug = New NotesLog("Router log")
     dbug.LogActions = True
     dbug.OpenAgentLog
     dbug.LogAction("begin")
     
     
     Open "c:\\umapada" & FileName & ".txt" For Output As #1
'REM Log the subject name of the message for debug purposes
     user = session.CommonUserName
     Set doc = session.DocumentContext
     Ifrom = doc.from(0)   ' this  fails  ..any reason
     dbug.LogAction("umapada" )
     Set it = doc.GetFirstItem("Subject")
     Write #1, "Subject "
     Write #1,it.Text
     Write#1,"****************************************************************************"
     dbug.LogAction("doc subject from context" + "-> " + it.Text)
     Set rtitem = doc.GetFirstItem( "Body" )
     Write #1, "Body"
     Write #1, rtitem.Text
     Write #1,"****************************************************************************"
     dbug.LogAction("Mail preprocessing agent is done")
     dbug.Close
End Sub



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Any comment will be highly appreciated.

thanks in advance,
umapada