Otdfbt

I have a vhost which I'm trying to get to work with LDAP-authentication. My configuration looks like this:

<VirtualHost 0.0.0.0:80>
 DocumentRoot "/var/www/root/"
 ServerName myServerName
 ServerAlias http://myServerName.com/
 LogLevel debug
 ErrorLog "/var/log/apache2/svn_error_log"
 CustomLog "/var/log/apache2/svn_access_log" common

 <Directory "/var/www/root/">
 Allow from all
 DirectoryIndex index.php
 </Directory>

 <Location "/">
 AuthType Basic
 AuthBasicProvider ldap
 AuthzLDAPAuthoritative off
 AuthName "Auth"
 AuthLDAPURL "myLDAPURL"
 AuthLDAPBindDN "myLDAPBindDN"
 AuthLDAPBindPassword my-safe-password
 Require ldap-group OU=Users,OU=A,DC=B,DC=C,DC=D
 </Location>
</VirtualHost>

When I try to login, it refuses my authentication and states in the log:

auth_ldap authenticate: using URL myLDAPURL
auth_ldap authenticate: accepting username
auth_ldap authorise: require group: testing for group membership in "OU=Users,OU=A,DC=B,DC=C,DC=D"
auth_ldap authorise: require group: testing for member: CN=username,OU=Users,OU=A,DC=B,DC=C,DC=D (OU=Users,OU=A,DC=B,DC=C,DC=D)
auth_ldap authorise: require group "OU=Users,OU=A,DC=B,DC=C,DC=D": authorisation failed [Comparison no such attribute (adding to cache)][No such attribute]
auth_ldap authorise: require group: testing for uniquemember: CN=username,OU=Users,OU=A,DC=B,DC=C,DC=D (OU=Users,OU=A,DC=B,DC=C,DC=D)
auth_ldap authorise: require group "OU=Users,OU=A,DC=B,DC=C,DC=D": authorisation failed [Comparison no such attribute (adding to cache)][No such attribute]
auth_ldap authorise: declining to authorise (not authoritative)
access to / failed, reason: require directives present and no Authoritative handler.

What am I doing wrong here?

I tried AuthzLDAPAuthoritative On with the same result. Also I'm sure, the LDAP is working properly, since when I only Require valid-user instead of an ldap-group, it works fine.

Should you be using Require ldap-group instead of Require group?

Also, if group members are identified by values of, say, the uniquemember attribute of the LDAP group, then you'll need to add AuthLDAPGroupAttribute uniquemember.