ePub format failing to embed font

[Fiona]

I document a programming language that requires a particular unicode font. I can include the font in Flare, use it in topics and successfully generate pdfs that have the font in. However, I'm now trying to generate an ePub file (haven't even looked at MOBI yet!) and I'm not having any luck. Although I have specified the "Embed Fonts" option in the target's "EPUB Options" tab, the font isn't coming across. Is there something else that I should be doing?