The following information will help ensure we understand the exact situation and thus can give accurate answers.
1. What is your contract size?
2. What is your use year month?
3. What is your home resort?
4. Given specific use years, such as 2005, 2006, etc, what points have been used for reservations?
5. Given specific use years, such as 2004, 2005, 2006, have any points been banked or points borrowed to a different year.
6. Were any banked or borrowed points used to make any reservation?
In your case it sounds like you either used banked 2004 points, or borrowed 2006 points, to make your 2005 use year reservation. That's why if you cancel that reservation, those returned points cannot be banked. Or maybe it's because you're past the 100% banking window, and already banked some points into 2006, so you can only bank 9 more.
If your BWV reservation was a mixture of banked/regular or regular/borrowed points, and you change it to OKW, then of the points returned, how many are regular points and how many are either banked points or borrowed points.
Trying not to confuse you, but the more information you can give the more we can help.