Showing a modal dialog box or form when the application is not running in UserInteractive mode is not a valid operation. Specify the ServiceNotification or DefaultDesktopOnly style to display a notification from a service application.
Source Error:
Line 50: con.Close()
Line 51: con.Dispose()
Line 52: MsgBox("Item with 'Item ID: " & itemID & "' & 'Item Name: " & itemName & _
Line 53: "' has been added to the cart!")
Line 54:
...
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