"Mailing Lists" link has disappeared

Hi, I'm using Virtualmin for years, and now I have a problem.

When I login in a normal virtual domain account, The link Virtualmin->Services->Mailing Lists is not shown. The link is shown when I login in a root account and any operation is worked.

I directly access to https://*******:10000/virtualmin-mailman/ in a normal virtual domain account, so the message is shown as follows:

Access denied : User **** is not allowed to use the Virtualmin Mailman Mailing Lists module I definitely checked "Allow Mailman mailing lists?" feature so it doesn't make sense.

Anybody knows where this problem come from and how to solve it?

Thanks,