"Can Not Connect to Asterisk" problem?

i have installed asterisk over ubuntu 12.04. Than i have installed freepbx but when i log in freepbx right-top side of the page it says “Can Not Connect to Asterisk”. How can i fix that problem?

try rebooting the system or manually starting asterisk

For reference on how to start & stop asterisk:
http://www.voip-info.org/wiki/view/Asterisk+Starting+and+Stopping