WDS network and Airtunes

I have a WDS network as follows: TC hard wired to AX n which connects wirelessly to an AX b/g that is only used for Airtunes. It works great.
But I tried to duplicate it at a friend's house; the only difference is that her TC is wired to an AX b/g which we want to connect wirelessly to another AX b/g for Airtunes. Works great for internet at both from both the TC and the AX hard-wired b/g. But we can't get her last AX to work on Airtunes; it stays flashing yellow. I duplicated all the settings (e.g., "participate in a network", other checkboxes, etc) exactly. Any advice? Could it really be that the fact that mine runs through an AX n and hers through an AX b really be the difference? Other ideas?
Thanks!