I have Webmin 1.3 running in a non-sparse zone and can't get past this error when trying to adda module.

I have webmin running in other zones fine without this issue.

I can't find a solution in the mail archives either.
Any hints? Can I get around this?

Webmin module cannot be installed or managed when the Webmin code is shared with another system, such as when it is running inside a Zone or mounted via NFS.