Trouble rendering with TBoundsphere

Hi,

    I have a problem with the rendering of an object in the world. First, i create a cube and specify a TBoundSphere surrounding it. After having the TBoundSphere, the cube seems to have problems rendering itself, it becomes invisible at some angles to the avatar meaning, if i move around the cube, at some points, the cube will just disappear but it'll appear again at other points. It renders fine without the TBoundSphere. Has anyone encountered this problem? By the way, the cube can have different length, width and depth. The TBoundSphere is centered at the center point with a radius which is the maximum value between the length, width and depth.