ORM Profiler Team
The Hague, The Netherlands
the application using the 3.5 code is leading, so if that's a .net 4.5 app and uses async, you need the .net 4.5 interceptor as there the async methods are intercepted.
If you don't use .net 4.5 async stuff, you can use whatever interceptor you want. The thing to remember though is: if you use entity framework, you have to use the right interceptor for entity framework. (you don't say what data-access framework you use).
Also be sure to place the interceptor init call at the very first step of your application, e.g. in the global.asax or if that doesn't work, try to place it in the first page's code behind that's opened. The key is to have the init call before any static constructors run on the orm framework used.