I was going through the source code of the TFS build extensions and came across the following TODO in TfsBuildExtensions.Activities.CodeQuality.StyleCop
//TODO: figure out why comilation breaks if we move StyleCop declaration into the namespace
I could not help myself and needed to find out why and resolve it.
The class is called StyleCop and when adding a using StyleCop the names collide.
Use the following using within the namespace:
Hope this helps.