First login to WAP with Directory Manager -> no button "Add User"

[Honza Burian]

Hi all.

When I successfully logged in to kolab WAP with cn=Directory Manager
(first login) I don't have here button "Add user" as is in this HOWTO:
http://docs.kolab.org/howtos/kolab-webadmin-create-user.html
Ok, there is a link
http://docs.kolab.org/administrator-guide/faq.html#faq-no-add-user-button-or-link

But it didn't help. SElinux is in permissive mode. DNS is ok.
Firewall? Where it could be problem?

Any error which I find is:
- - - - -
# less /var/log/kolab-webadmin/errors
[11-Sep-2014 23:36:09 +0200] PHP Warning:  exec() has been disabled
for security reasons in /usr/share/php/Net/LDAP3.php on line 754
- - - - -
This error occurs 7 times after I logged in to kolab WAP.

I don't like to allow exec() function globally. And don't know if its
possibly help. Any idea?
Any help will be appreciate.

Best Regards
John