Newbie: virtual hosts and includes

[Wi...@Bertelsmann.de]

The scenario:

A script under a shared location (/www/shared/myscript) parses a html template and print it out.
For each virtual host exists a template with the same name but different root directories:
/www/a/htdocs/templates/mytemplate
/www/b/htdocs/templates/mytemplate	... and so on (root: /www/?/htdocs)
Each template includes a header with a relative path to its root 
(ex. /headers/myheader located under /www/a/htdocs/headers/myheader).
Weird, but all files have to remain where they are.
Under mod_cgi it works fine, with mod_perl I get sometimes the right template but with a
header from another virtual host 
(ex. /www/a/hdocs/templates/mytemplate includes sometimes /www/b/htdocs/headers/myheader).

My configuration:

PerlWarn On
Alias /bin/	/www/shared/myscript/
<Location /bin>
        SetHandler perl-script
        PerlHandler Apache::PerlRun
        Options ExecCGI
        PerlSendHeader On
</location>
<Files */nph-*>
    PerlSendHeader Off
</Files>

I read the dokumentation but even the 'dirty configuration' didn't help.
Hope anyone can help me :-)
Thanks,

Winni