Textile 1 plugin problem

I’m using the Textile 1 plugin that comes with WordPress but for some reason it’s not displaying the titles for acronyms. For example, if I write CSS in an entry, a little tag should pop up that says Cascading Style Sheets.

The interesting thing is that my mouse cursor changes to a questionmark, like it should, but just does not display the title. Anyone have any idea what’s going on?

Thanks in advance for any help or insight!