add these repositories in your  sources.lits for ubuntu Feisty:    in  /etc/apt/sources.list

sudo nano /etc/apt/sources.list

deb http://ubuntu.beryl-project.org feisty main" | sudo tee -a /etc/apt/sources.list
deb-src http://ubuntu.beryl-project.org feisty main" | sudo tee -a /etc/apt/sources.list


ctrl + x,   confirm by "y"  which is yes,  enter