Default [Q] Rooted XS not working with Android Device Manager

I have an XS running 6.2.B.1.96, rooted with DoomLord's technique. It has latest Google Play Services.

I'm trying to get the phone to play ball with Google's Android Device Manager. It appears in the list of devices, but ADM gives "Location unavailable" when I try to locate it, and it does not respond to commands to lock or ring the device etc.

ADM is enabled as a Device Administrator in the security setttings, I've cleared the Google Play Services data as per the help pages, but no joy so far.

Has anyone else had the same problem? Any ideas on how to resolve it?