how to set selected item in dropdown box?

   in my scenario i want to select the default value for the drop down list per the value in some session variable at the time?
plz tell me how to achieve this...
i try
    If Session("Department") <> "" Then
         Me.DDLDepartments.SelectedItem.Selected = Me.DDLDepartments.SelectedItem.Text = Session("Department")
    End If
but its not working..  
thx..
 
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