Simple simulation problems.

[PaloDeQueso]

I have a static height field for terrain and a sphere which is dynamic and rolls around nicely. However if I replace the ground with a static box for collision, the sphere will bounce once and then fall through. I'm using the most basic setup possible as described in this tutorial, http://www.bulletphysics.com/mediawiki- ... ello_World. Does anyone have any suggestions for finding out why this is happening?