Does it have any relation with multiserver support ? because in Wikipedia they said that Ajenti didn't support this feature yet.
See this link: https://en.wikipedia.org/wiki/Comparison_of_web_hosting_control_panels

Well i figured how to install the most plugins to have the Website section in Ajenti.

After installing Ajenti on Ubuntu 14.04 you just need to install those packages:

apt-get install ajenti-v agenti-v-nginx ajenti-v-mysql ajenti-v-php-fpm php5-mysql

Then everything will be allright.

Now i'm figuring how to install the webmail ...