Can't duplicate collection

Whenever I want to duplicate a collection and it’s contents… I click on the collection in the outliner, rightclick and select ‘duplicate collection’… however… im getting this error:

“no active collection”

What does this mean and how can I fix this? Im in blender 2.91 Cycles

Did it work for a new empty file?

The “No Active collection” sounds like you haven’t actually first left-clicked on the collection to make it active, so it has nothing to select.

Thanks for your answers…

And yes, it seems to work on a new and empty blend file… so im not sure why it doesnt work on my project file…

edit: i copied the project file and it seems to be working again…thanks for your help anyways!