Denemo doesn't display characters correctly

[Denny Lin]

Hi, I installed audio/denemo yesterday, and it doesn't display
characters correctly (notes and treble clef). A PDF export is ok though.

Screenshot here: http://security-hole.info/~dennylin93/tmp/denemo.png

Should look something like this instead:
http://upload.wikimedia.org/wikipedia/commons/e/e5/Screenshot-Denemo.png

How can I rectify this? Thanks.

-- 
Denny Lin