Considering that there are only 6 faces defined in the .blb file, it's likely that's because your brick is actually a box.
I don't know how 3D2BLB works, but its not a good idea to try and make a brick if you know nothing about reading/editing .blbs, you'll likely just make something that sucks / is broken. Porting models directly from LDraw into Blockland without any sort of cleanup is also something you should never do if you care for your brick's efficiency.