[Plugin: WordPress SEO by Yoast] keyword density is % in 1.2.3

I just updated wordpress seo by yoast.
But there’s a problem. When I write a post, and save a draft, the seo check list for keyword density is always like this:

The keyword density is %, which is a bit low, the keyword was found 6 times.

It doesn’t show any keyword density percentage.

My blog is 静思学吧(http://www.jsxubar.info) , which is a chinese wordpress blog.

What should I do, how to submit my debug information to you?

http://wordpress.org/extend/plugins/wordpress-seo/