That exception means that you are trying to instantiate an
interface (IUnityContainer), and not the
class that implements that interface, which in this case is
UnityContainer. If you want to create a new container, you could write something like:
IUnityContainer container = new UnityContainer();
IUnityContainer container = new IUnityContainer();
As for the reference, in every project that you use the Unity Container, whether it is the shell or a module, you must add a reference to the
Microsoft.Practices.Unity assembly. You can find that assembly in the LIB folder that comes with Prism. Inside the StockTrader RI, there are references to it in the shell and all its modules.
I hope you find this helpful.
Guido Leandro Maliandi