billy bob.....both files contain a backgroud.
I looked at your test level and the background didn't show up so I opened it in the editor...well... the folder is named colour
fulsquares and you have it named in the editor as coloursquares.
If you would the background texture also needs to be
resized.
64x64
128x128
256x256 or
512x512
The same as textures.