Did the function HTXML_write forget to write stream to the "target" stream?

Hi, I'm new to libwww, and have a question about downloading XML with it.
I set up the example program, when I used it to download HTML pages and
images, it worked well. But when I switch to XML, it failed to write the
file to harddisk. According to the log, the program had got the content of
the XML, but didn't write it down.
I traced the program and finally focused to the function HTXML_write(HTStream
*me, const char *buf, in len) in HTXML.c
I think this function should write the content to the target stream in the
param HTStream "me", after doing the XML_Parse work, just like what it did
in function HTXML_abort.
I added a line of code
   (*me->target->isa->put_block)(me->target,buf,len);
before the return of HTXML_write. Then it worked here.
Is this a bug? Or the fault of my programming? Wish someone can help me.
Thank you

-- 
Wei Wei