Can't get boolean modifier to work? I'm trying to use the boolean modifier to "etch" the logo into a block, but it is giving the error "Cannot execute boolean operation".

The file can be found here http://www.pasteall.org/blend/43089

I would greatly appreciate any assistance as I'm practically brand new to blender. 

Thank you in advance!
Select logo go to edit mode press W and Remove doubles.

Then set the Boolean modifier to Difference.