Axios Xaris

I've made considerable progress in learning this Mesh thing although I've been finding it rather finicky lately. Using 3dSMax, I've been making simple building components necessary to build a new home inworld and made to save prims. Thus far I've successfully made and uploaded most of them but there is this one simple mesh in the shape of a hollow octagon that I need to make an octagonal room that just wont upload at all for some reason when I try to calculate the cost with the physics settings on high. I need the physics set on high because I want to make it possible to move inside the room. This would not be possible with any settings lower than that. But I mean for gods sake, it is only a simple object that does not have very many triangles at all. But still I keep getting this MAV_BLOCK_MISSING message. Just what does this mean?