"Unable to read group information from repositories" during RHEL 6.9 NON-networked install

I'm trying to set up a machine that's not on a network. I have a "repo-drive" (USB external) containing a kickstart file created by some guys who used to work with me, and I have a 6.9 (original, not update 7) full binary DVD. I boot off the DVD, hit tab at the boot screen and append ks=hd:LABEL=repo-drive:/blah/blah/blah.cfg and the kickstart gets as far as partitioning and formatting the drive, but when it gets to the package list, I get the ever popular "Unable to read group information from repositories. This is a problem with the generation of your install tree."

I'm not unfamiliar with RHEL, but never had to troubleshoot a kickstart. So far, I've made sure I had a full binary DVD, as opposed to one that would expect a network, and made sure all the directories on the "repo-drive" are world-readable to avoid any permissions problems. No dice. I've seen some discussions online mentioning .treeinfo or .repoinfo files, but I'm not sure where those would be - on the DVD or on the "repo-drive" or indeed where the "install tree" would be. Searching on here, I found https://access.redhat.com/solutions/364364 and https://access.redhat.com/articles/1476 not those appear to be specific to network installs while this machine has no network at this time, and will not have Internet access.

Any suggestions are appreciated. Thanks!

Dan