Failure to Bind ModelView to TabControl in WPF using MVVM

I am attempting to bind a ViewModel to a TabControl in my MainWindow. I have everything wired up in my application, but the tabs are not being added.

I have a MainWindow which has an associated MainWindowViewModel. I have a ResourceDataViewModel, which is the ViewModel for the full resource data set and a ResourceViewModel - a view model for each resource in the ResourceDataViewmodel data set. This is to allow me to do UI related things with individual resources at a later date. There is a lot of code that could be affecting why this is not working as I am using a couple of layers of inheritance to enable tab items to be added from different sources; as such I have uploaded the solution for inspection.

If anybody could point out what I am doing wrong that would be most appreciated as I have spend the entire weekend on this and have hit a brick wall in trying to get this working as it should. These files are on the sky drive and are editable:

http://sdrv.ms/12aLLIc

Thanks you very much for your time.

"Everything should be made as simple as possible, but not simpler" - Einstein