Internal Server error and web traceback when editing RHEL4 kickstarts

Issue

• Created 2 RHEL4 kickstarts by cloning from existing, working RHEL 6 kickstarts. The kickstarts are up and runing, just built a server and worked.
• Trying to add some packages on the software section results in a server error and now anything done on these kickstarts now fails (all the others still working fine).