mkkickstart is hopelessly broken in RH 7 due to filesystem labels in /etc/fstab--because of the new filesystem labels it will not generate correct "part" entries. mkkickstart probably needs an overhaul to work properly. I'd patch it myself but I have no idea how to dump filesystem labels off ext2 filesystems yet...
*** Bug 19229 has been marked as a duplicate of this bug. ***
*** Bug 21673 has been marked as a duplicate of this bug. ***
mkkickstart isn't supported anymore, closing WONTFIX