Custom Display, CalculateBoundingBox, Frustrum Update, c#

Hello,

I've been struggling, now for a while, to write a custom display that doesn't produce a pipeline error. I believe that the error might originate from my not knowing how to update or add my geometry to the Bounding Box.  Would someone be kind enough to provide a small amount of c# assistance here?

References (including my code - link from last entry) are posted here:

http://www.grasshopper3d.com/forum/topics/custom-display-seemingly-...

A code example written by david (that I used as a basis for my code in) is given here about half way down the page see "FrustumUpdate" attachment:

http://www.grasshopper3d.com/forum/topics/frustrum-frustration

I note that there is no visible use of a bounding box in this code either...