Irrlicht Engine

Hi All,
I am experiencing a wierd problem with the Bullet Physics engine (the latest version).
Actually, I have a convex hull mesh (a dynamic object), which falls through the static plane quite randomly. I don't know why it happens, but I find this happening with no reason at all. The normal behavior is for the object to bounce off the ground plane, but it instead sometimes penetrates the ground and falls down (and subsequently becomes out of sight) as if there was no ground plane at all to collide with. I tried to reproduce the issue with the same amount of force applied, but sometimes it works fine, and sometimes it penetrates the ground and goes down infinitely away.

The meshes for the objects I am using is created in a 3d software. The dynamic object is a Sphere, and the static plane object is a Plane.

Is there a reason why this is happening or has somebody else encountered such an issue?

Thanks

Why ask about a problem that is confined to Bullet on this forum? Your best bet is to go to the Bullet forum (assuming they have one) and ask there as there will be many more Bullet users there

I will ask in Bullet forum but I am asking here because I don't find it connected to Bullet alone, but its probably something because I am using Bullet in Irrlicht. I thought someone may have experienced such an issue here and may point me in the right direction.
I haven't experienced such a problem while using bullet's examples in openGL.

I have had a similar problem with ODE because I didn't use a fixed time stamp but calculated the time between two frames and passed that value to ODE.