Excellent video but I'm having a problem with the app.config. I believe mine is correct but as soon as I remove the CalculatorLibrary reference, the InputOutputLibrary reference, or the CalculatorCommandParsingLibrary reference. I get a FileNotFoundException for the reference I remove. Any help would be appreciated.

Update: I realized that when my references were being deleted that they were deleting the dll's from the bin. All is good now.