[Plugin: Markdown QuickTags] Looks fine in Preview, but doesn't work

MDQT does not render anything on the front end. If you don’t want to run a Markdown plugin (Like PHP Markdown Extra) on the front end to convert Markdown at the time of display, you need to use “Render” to convert the Markdown to HTML, then save your post with the HTML instead of the Markdown.

There’s a great plugin called “[Markdown on Save][1]” that will save the HTML in the post but keep a copy of the original Markdown in the database. Thus, you get HTML on the front end, but when you go back to edit the post you still have Markdown.

[1]: http://wordpress.org/extend/plugins/markdown-on-save/