[Plugin: WP Minify] Combining JavaScript files

I started using WP-Minify because of suggestions such as the following when testing my sites at Pingdom.com:

There are 4 JavaScript files served from http://www.vietnam-travel-guide.net. They should be combined into as few files as possible.

When I rerun a test at Pingdom.com I see no change.

Does that mean that WP-Minify isn’t working on my site?

Thanks

http://ww.wp.xz.cn/extend/plugins/wp-minify/