Take a look at Jay's second picture above. That is how you eliminate those odd shaped panels.
When coming into any corner with a board or molding that is on an angle (like the stairs for instance), you must first miter that board or molding so it is perpendicular to the corner before going around it, whether it is an inside or outside corner.
To be truthful, I don't have a clue what you are talking about, however. Are the boards between your panels (stiles) vertical?
Last edited by clampman; 07-07-2011 at 12:34 PM.