RachelRachel 133k6767 gold badges315315 silver badges510510 bronze badges two three Rachel, you are an attractive genius!!! And I am an idiot. Thanks a lot of for the answer. I had been binding to self and did not have a 'ConfigurationModel' property in my IncrementingTextBox class. So your DataContext for "video_length_textbox" https://diigo.com/0zy04m