apt-get install : couldn't find package 的解決方式

#apt-get install joe

Reading package list… Done
building dependences list… Done
E: couldnt find package

#vi /etc/apt/sources.list

deb http://tw.archive.ubuntu.com/ubuntu/ edgy-updates main restricted
deb-src http://tw.archive.ubuntu.com/ubuntu/ edgy-updates main restricted

deb http://tw.archive.ubuntu.com/ubuntu/ edgy universe
deb-src http://tw.archive.ubuntu.com/ubuntu/ edgy universe

deb http://tw.archive.ubuntu.com/ubuntu/ edgy-backports main restricted universe
deb-src http://tw.archive.ubuntu.com/ubuntu/ edgy-backports main restricted universe

deb http://security.ubuntu.com/ubuntu edgy-security main restricted
deb-src http://security.ubuntu.com/ubuntu edgy-security main restricted
deb http://security.ubuntu.com/ubuntu edgy-security universe
deb-src http://security.ubuntu.com/ubuntu edgy-security universe

#apt-get update

#apt-get install joe