Hi Matt,

Have you checked the KeyboardNavigation.TabNavigation property? This property controls how navigation is handled in WPF containers.

Focus can fail for any of the following reasons:-

1] Element Enabled = false
2] Element IsVisible = false
3] Element Focusable = false

Or

4] Element is in a control and not the main xaml (not been loaded)
5] LostKeyboardFocus and PreviewLostKeyboardFocus are preventing it

Where you are trying to set the Focus in your code put a new line in that makes a call to the textbox PredictFocus method and set a breakpoint. PredictFocus will not shift the focus but it will tell you what should be focused next and help resolve containers that are not releasing the focus.

HTH
Neil