To handle the LDAP realm inside WebOffice 10 R3 the Tomcat authentication has to be set false (<Tomcat installation directory>\conf\server.xml):
<!-- Define an AJP 1.3 Connector on port 8009 -->
<Connector port="8009" protocol="AJP/1.3" redirectPort="8443"
tomcatAuthentication="false" />
Restart the Tomcat service after configuration.