> Have you created quotas in the first place? I seem to vaguely remember
> that you can get the message you got when no quotas have been set yet.
Yes, I used quotas and quotatool without problems for years. But some day - unfortunately I don't know when - it stopped working. Because quotatool was always called by a script I did not recogize the error a long time. It is possible that it happened after the upgrade to Wheezy...