How to fix AdDuplex ad unit configuration error for Microsoft AdMediator

The following error message "Ad unit configuration error Please check the configuration" kept popping up in the Microsoft AdMediator control in an Windows Phone 8 app when it tried to display an ad from AdDuplex.

After troubleshooting the issue, I found that the AdDuplex configuration was indeed incorrect. To resolve the issue the following must be done.

1. In the Visual Studio project, right click on the project with the AdMediator control. Choose Add | Connected Services.
   
   The Services Manager dialog box appears.
   
   
2. Select AdDuplex. Click Configure.
   
   The Configure AdDuplex dialog box appears.
   
3. Note that the dialog is asking for App ID.
   
4. In a web browser, open up the AdDuplex app detail page that you want to show ads for https://manage.adduplex.com/#/apps.
   
   
5. Important: Instead of using the App key as it says on the page, copy the Ad unit ID value at the bottom of the page, e.g. 123456.
6. Now back to the desktop's Configure AdDuplex dialog box. In the App ID field, type in the value from the web page Ad unit ID, e.g. 123456. Click OK.
7. In the Service Manager dialog box, click OK.
8. Build and run the app.
   
   AdDuplex ads will start appearing correctly in the AdMediator control.