FreePBX doesn't save config

Hello, everybody!
I’ve installed FreePBX 12 on fresh install of CentOS 6.5 as it described in wiki. Now when I add settings in System Admin -> Network Settings or DNS and click Save, it thinks for a few seconds and displays page with old settings, it doesn’t save them. The only error, that I got during installation process was in Set ownership permissions. section. After
chown -R asterisk. /usr/lib/asterisk
I’ve seen error “File doesn’t exist” and after
mkdir /var/www/html
I’ve seen “File already exist”, so I’ve done
mkdir /usr/lib/asterisk
chown -R asterisk. /usr/lib/asterisk
chown -R asterisk. /var/www/
And else I have a question, what should I write in Default Gateway, if my machine is running in AmazonAWS EC2 instance.

The wiki assumes a default base install. I would assume your EC2 install is not a vanilla install but rather a EC2 optimized install. This means some of the underlying plumbing may differ. One of those things may be not allowing you to mess with network settings.