Default Variable problem

I setup a TV based on the create TV based chunks tutorial with the exact same information except I added a default variable.

http://wiki.modxcms.com/index.php/Create_TV-Based_Chunks

Everything works fine except I cannot save a page with the default variable unchecked. Everytime I uncheck and save it just goes back to being checked.

I found some threads with similar problems to mine.
http://modxcms.com/forums/index.php/topic,6464.0.html
http://modxcms.com/forums/index.php/topic,4697.0.html

but was unable to find a suitable solution. Anyone have any ideas? Thanks.

As per this post I understand why it wasn’t working. Thanks

http://modxcms.com/forums/index.php/topic,22616.0.html

I fixed it by adding another chunk that did nothing called none instead of leaving it blank.