DOCBOOK: ULink problem in PDF produced with Saxon/FOP

Hi all,

I've finally run into a problem that I can't find any other online 
references to!

I've got a DocBook 4.1.2 document that I want to make available in XHTML 
and PDF format.  I've been using Saxon and the DocBook XSL stylesheets 
1.57.0 to do the conversions, and FOP 0.20.3 to process the resulting FO 
file into PDF.

XHTML output is a breeze, no worries at all.  However, in my PDF files 
the URLs from a Ulink tag aren't working.  For example, say I had this 
ulink:

<ulink url="http://somesite.com">http://somesite.com</ulink>

In the PDF file the linked text would show correctly as

http://somesite.com

But upon mousing over the linked text in Acrobat Reader, the link URL 
shows up as:

url(http://somesite.com)

Which means they don't work when clicked upon in Acrobat reader; what I 
need is for the link URL to be simply

http://somesite.com

I've been over the FO stylesheet parameter reference a few times, but I 
can't find anything that might cause this behavior.  I'm not familiar 
enough with XSL or FO to determine whether the problem is with the 
stylesheet or the way FOP processes it... has anyone reported this 
problem before?

Many thanks for any insight anyone can give me!

Best regards,

-Andy Chase