[Plugin: WP Minify] 400 Error

I have installed it. Default settings. All folders/files are writable as needed.

I go to the website, and the minified CSS/JS is giving me 400 http error.

So I go into advanced settings, and select “Combine but don’t minify”.

Still 400.

What gives? Does this work or not?

http://wordpress.org/extend/plugins/wp-minify/