LXC container and quota

Hi folks, I want to run Virtualmin inside a LXC container. Both the host and the container are Ubuntu 14.04 systems. So far all is working except support for quota seems not to be there. The root filesystem is mounted with usrquota,grpquota options. Looks like quota is enabled when running the mount command:

/dev/vg0/lxc1 on / type ext4 (rw,usrquota,grpquota)

But trying to enable quota in Virtualmin does not work neither using the command line tools:

# quotacheck -cum / quotacheck: Cannot stat() mounted device /dev/vg0/lxc1-backup: No such file or directory quotacheck: Mountpoint (or device) / not found or has no quota enabled. quotacheck: Cannot find filesystem to check or filesystem not mounted with quota option.

The container file system is located on LVM. Anyone has an idea how to make this work?