Distribution list checked as hidden not showing in admin

[digital at usina-de-imagens.com.br]

Hallo,

> > Would someone please tell if this is the normal behaviour [...]
> No, this is definitely not the way it should be - I have some hidden
> lists showing without problems in the admin interface.
Thank you for the answer

> Do you have anything strange in your log files?
Not that I could detect.
But I found out something: The domain used initially has not an DNS MX record 
pointing to this server. If I change the domain to one that is pointed by DNS 
to this server it shows up.
So I guess I found the origin of the problem. But why does it behave like 
this?

TIA,
JK