When I try to import System.IO.Packaging onto my windows application. I am not able to find it. However after doing some research online, realise that I need to add the WindowsBase.dll reference before I can import the System.IO.Packaging namespace.
Here it is the solution:
1) In the “Solution Browser”
2) Right Click on “Reference” ->”Add Reference..”
3) On the “Add Reference” windows, click on “.Net” tab
4) Then find.select “WindowsBase” on the list below
5) Click “Ok” to add the references.
6) You should be able to import System.IO.Packaging namespace.
*however, you cannot import System.IO.Packaging namespace in Silverlight Application =(