Can't create a sub -group in RDCMan 2.90

Question

I'm not sure when it started.
Let's say I work at a company who has 2 divisions. So i separate each division as a group. But when i want to create a group off them by right clicking on the group name, "Add group..." and "Add smartgroup..." are greyed out. i can only create a server.
If I create a group and try and drag it within another group, it doesn't work.
This goes back to at least v2.82 - but I never needed it until know but I did previously have subgroups and they are there.
[And yes, I could manually edit the .RDG file.]
Thanks

Answer 1

Create a new RDG file, then create group in this new file, then drag drop Connection to your newly create group. Voilà!

Answer 2

Old question but I may have the answer.
You can't add new groups in if you already have a server inside that group :-)