Boolean Modifier Trouble I'm having trouble with the Boolean difference modifier. It isn't cutting out some pieces of the mesh:


With the difference mesh hidden (note the lack of the rectangular cutouts)


All the normals are in order:



The modifier is not showing any errors or warnings.
Paste all .blend link 

In addition to any potential solutions I'm also interested in the description of situations when it happens and an explanation of the cause.
You can fix this problem by first triangulating the mesh you wish to carve holes into. The large ngons on the top and the bottom make it hard for blender to create these holes.


Go into Edit Mode, Tab
Select the mesh you wish triangulate, A or hover mouse of mesh and press L
Triangulate the mesh, CtrlT


You will notice that the error message under the modifier is now gone.