Apache2; mod_autoindex, HeaderName & DocumentRoot.

I'm having a problem or two with Apache 2 & the header I wish to
include for my auto-indexed directories. I can't seem to work it out,
and am hoping someone can help me.

I have a number of virtual hosts, and I want each one of them to
include the same header for their directory index - for instance if I
wanted both user1.stroller.uk.eu.org & user2.stroller.uk.eu.org to
have a link to a banner ad at the top of all of their pages, including
user1.stroller.uk.eu.org/foo/ & user2.stroller.uk.eu.org/bar/

So in /etc/apache2/conf/commonapache2.conf I have sections that look
something like this:

<IfModule mod_alias.c>
Alias /icons/ /home/httpd/icons/
Alias /markup/ /home/httpd/markup/
Alias /doc /usr/share/doc

</IfModule>
# End of Alias directives.

<IfModule mod_autoindex.c>
# FancyIndexing is whether you want fancy directory indexing or
standard
IndexOptions FancyIndexing VersionSort NameWidth=*
SuppressHTMLPreamble

# AddIcon* directives tell the server which icon to show for
different
# files or filename extensions...
AddIconByEncoding (CMP,/icons/compressed.png) x-compress x-gzip
AddIconByType (TXT,/icons/text.png) text/*
....
# DefaultIcon is which icon to show for files which do not have an
icon
DefaultIcon /icons/unknown.gif

# ReadmeName is the name of the README file the server will look
for by
# default, and append to directory listings.
# HeaderName is the name of a file which should be prepended to
# directory indexes.
#
# ReadmeName README.html
HeaderName /HEADER.shtml
# ReadmeName FOOTER.html
ReadmeName /FOOTER.html

# IndexIgnore is a set of filenames which directory indexing should
ignore
# and not include in the listing. Shell-style wildcarding is
permitted.
IndexIgnore .??* *~ *# HEADER* FOOTER* RCS CVS *,v *,t

</IfModule>
# End of indexing directives.


Note that the mod_include documentation <http://tinyurl.com/rfyr>
says:
"Both HeaderName and ReadmeName now treat Filename as a URI path
relative to the one used to access the directory being indexed. If
Filename begins with a slash, it will be taken to be relative to the
DocumentRoot."

$ grep -i DocumentRoot /etc/apache2/conf/apache2.conf
DocumentRoot /home/httpd/htdocs

But if I stick the HEADER.shtml in that directory and browse to
http://user1.stroller.uk.eu.org the contents of that header are not
shown before the file listing. "Ah!", you say, "but that's a virtual
host yada yada yada", and true, when I move HEADER.shtml to
/home/httpd/htdocs/user1.stroller.uk.eu.org/ it is displayed
correctly.

But right now, it's contents are only:
<!--#echo var="DOCUMENT_ROOT" -->
and it's output is "/home/httpd/htdocs/"

So I'm right confused. You can see that I've also got:
Alias /markup/ /home/httpd/markup/
in my configuration, but sticking the HEADER.shtml in there gives no
joy, either.

Is there any way I can put this file in such a place that all virtual
domains & all their subdirectories will reference it..?

Right now it seems that I can put a sym-link in the highest of each of
the virtuals' directories, and it works fine, but I'd prefer not to
have to, in case I forget sometime when I'm adding one.

Many thanks in advance for any suggestions,

Stroller.