Form-based authentication apache tomcat

[Andrew Robson <an...@netscapeonline.co.uk>]

This is my first post to this list so I hope my problem isn't
too stupid. I'm using tomcat 3.2 , mod_jserv, apache on redhat 6.2.
I'm trying to implement form-based authentication. 
I've got the jsp example in Tomcat 3.2 to work when running
through tomcat only. However when I try the same thing through 
apache after submitting username and password I get a 404 for request
/examples/jsp/security/login/null I don't know why the null is getting
appended but it squares with the message tomcat is sending out 
" Ctx( /examples ): 404 R( /examples + /jsp/security/login/null + null) null"

There a couple of peculiar aspects to this. When I try and access a document
in the protected dir through apache there are two attempts to send the
JSessionID cookie to my browser.Suspect the request is getting garbled
becasue of this? Also even though I get the 404 error the j_username and
j_password appear to be getting set correctly because they show up when I run
the Session example. Even more irritating - if I simply try to access the
protected dir rather than a doc within it then everything works fine (perhaps
because the index is a jsp file??).I've had a good go at the configuring the
tomact apache conf file trying the various options in the minimalist guide.
I settled on  
ApJServMount /examples ajpv12://localhost:8007/root
as my best chance because I thought this would delegate 
the handling of all files under this directory to tomcat. 
Does anyone know what I'm doing wrong?
Many thanks
Andrew