Login fails in kolab-webadmin, mod_rewrite enabled.

[Henning]

Hi,

I cannot login via kolab-webadmin anymore.

apache-log:
client denied by server configuration: 
/usr/share/kolab-webadmin/public_html/api/system.authenticate

kolab-webadmin-log:
(jni80dfa0kn9v9d5b1mdssf1a0): PHP Error: Login failed. Unable to decode 
response (POST)

mod-rewrite in apache2 is ENABLED.

ldapsearch with 'cn=Directory Manager' works as expected.

What can I do to debug the thing?

Please help.

regards,
Henning