tabIndex and FocusManager confusion

I’ve got an app with about 10 input text boxes on each of 5 frames and a handful of nav buttons. I want the tab key to cycle between the text input boxes on a given screen and leave the nav buttons alone. According to the docs, if any on-screen element has a tabIndex set, auto-tabing is disabled. OK, I set the tabIndex properties on the first screen from 0 to 9 , tested and everything worked fine. I then added tabIndex properties to each of my text input boxes on the other screens starting from 0 on each screen. I tested and suddenly the tab order was Z order and included the nav buttons (ie it looks like auto-tabing was back on). On the off chance that every tabIndex had to be unique, I tried setting the tabIndex properties from 0 on the first element to 50 on the last screen, last element, still behaves like auto-tabing is on.

I see I can create focus loops to exert greater control over the tab sequencing but the meager example in the help docs isn’t much help. Am I doing something wrong with the simple setting of the tabIndex prop? Does anyone have a simple example of using the FocusManager?

Thanks.