Lilypond-book loses ℟ symbol

[Tom]

When using lilypond directly, the \set stanza = #"℟." for a response worked
fine. (If you can't see it, it is the Unicode response character described here:
http://www.fileformat.info/info/unicode/char/211f/index.htm ) However, when
including the same file with:

\lilypondfile[staffsize=15.87,line-width=15\cm,noindent]{file.ly}

the response character is lost. If I replace it with a more common Unicode
symbol (such as the (R) ® reserved sign) it displays correctly.

Any ideas why it wouldn't show up? Is there some way I have to tell
lilypond-book to include the character?

Thanks!

-tom