I started on 3.5 and it was my issue, it works great!!! http://thelibertycaucus.com/watchdog/slc to see it working if you need to.
My mistake, I had an input error on my tag slug adn it caused it to malfunction.
I have an issue where when using the shortcode above to display posts by tag onto a page it gives me an error. I am running 3.5 so that may or may not be an issue. Any ideas? I have not edited any page template with code and am trying to use shortcodes to display with the plugin activated