[cs615asa] Ubuntu package - sources list?

[Tejas]

Working through HW2 and I had no problem with Fedora and YUM. Using the AMI for Ubuntu (2nd on list) however, I can't find the package for 'screen' 	or 'sipcalc' the other ones were all already installed with newest versions. I've run 'apt-get update' and I've searched 'apt-cache' but it can't find either screen or sipcalc. I've checked online and those packages should be part of standard Ubuntu sources list. Do we need to go in and modify the sources list? Anybody have luck installing these 2 packages on ami-19a34270?