Are you using extended queries?
You should post a screenshot of your config page. Blank out anything you might feel is sensitive but do it in a way we can see all the strings.
you can also try and escape the space with \20 and see if that works
so
ou=OU WithSpace
becomes
ou=OU\20WithSpace
Or
might be %20 as escape for space. so would be ou=OU%20WithSpace
if you need multiple groups to be searched the authentication container string should look similar to this
CN=Users,DC=domain,DC=com;OU=DifferentUsers,DC=domain,DC=com
I use extended queries for my vpn access and it looks like this
memberOf=CN=VPNusers,CN=Users,DC=domain,DC=com