Monetizing win phone 8 app with Microsoft pubCenter

Ok, there are many online tutorial out there if you google, and they will guide you step by step from installing the Microsoft advertising SDK for win phone 8, register account at pubcenter… until getting the ads display on your app. For example, like this one:¬† However, I followed this tutorial but ads is not showing in my app. Something wrong. The debug output shows an exception message: Thanks to Chia Shaw Chyn that highlighted it could be a¬†missing capabilities issue. So i hook up a function onto this adControl object to track down the detail when error occurred. Ok… now it output debug msg like: To add missing capabilities, Goto Solution->project->properties->WMAppManifest.xml->Capabilities (tab), make sure you have the following ticks:
BOLD: are the one that the tutorial missed and is important to make sure they are ticked. For you who are interested, the complete code for my MainPage.xaml.cs is as below: