AuthUserFile directive not working?

[Anthony Treanor <anthony@perthweb.com.au>]

Hi,
	I've been trying to configure a .htaccess file on a new installation of 
Debian.
The authentication module is running, since this works

<Directory /home/prosourc/images>
AllowOverride FileInfo
</Directory>

.htaccess

ErrorDocument 404 test.html

IE if I access http://www.onexus.com/images/wrongstuff I get the correct 
response, a silly test page

If I try and configure the directory /home/prosourc/public_html/admin with

<Directory /home/prosourc/public_html/admin/>
AllowOverride AuthConfig
</Directory>

.htaccess file

AuthUserFile	/etc/apache/passwd
AuthGroupFile /dev/null
AuthName	"Test"
AuthType	Basic

require valid-user

And then access that directory from the web, I am prompted for a user name 
and password.
I enter the user name and password, but nothing really happens, the 
following line is in the log file

[Thu Dec  7 16:55:22 2000] [error] user dev not found: /admin

On Redhat it will tell you it can't find the authentication file in the 
error log.
I've tried

AuthUserFile I-dont-exist
...

and removing the AuthUserFile directive entirely and this doesn't make any 
difference to the error logged, I've been trawling the net for days, any ideas?

Anthony