Your google apps/sites dns is probably being served by another provider. Check the documentation: http://www.google.com/support/a/bin/answer.py?answer=48090
You have to ask your current DNS registar to modify your information. Do a whois lookup of your domain so you get to know who's your registar. -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To view this discussion on the web visit https://groups.google.com/d/msg/google-appengine/-/Y_vDUGgIADUJ. To post to this group, send email to google-appengine@googlegroups.com. To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.