combine require user and require group

Hi,

I try to use both require user and require group in .htaccess file.
My configuration only work with ONE directive "require user jan" or
"require group staff", but not both.

What I have done wrong here ?
Thanks
Minh

# cat .htaccess
AuthType Basic
AuthName "Password Required"
AuthUserFile /etc/httpd/conf/password.file
AuthGroupFile /etc/httpd/conf/group.file
require group staff
require user jen

# cat /etc/httpd/conf/password.file
joe:rxXCdbTQqmbYA
jen:xyVSuHLjceD92
jeff:bR0J3kdW2NuGA

# cat /etc/httpd/conf/group.file
staff:joe jeff


# cat httpd.conf
...
...

DocumentRoot /var/www/html/example
ServerName www.example.com

Options Indexes Includes
AllowOverride AuthConfig