Everything looks OK, except for the following:
In NetPro, for the PC280 you have to add a "connection".
Select the PC280 - OPC Server, and then click on the "spreadsheet" like list below the graphical layout, and a dialog for adding a connection will appear. Specify an "S7" type connection if you are in doubt. From then on it is fairly straightforward.
You can also follow my guide in the downloads section.