Members of a group can't add an group event

Dear stackideas,

We noticed that members of a group can't add an group event while admins and creators of the group can.
It would be nice if we could let all members add events in a group.

In the settings i found the right section but i can't set it to all members.
We can do this with every other sections such as file's and albums but not evens.

I've also attached a screenshot to clearify.

I would like to hear from you soon.

Kind regards,
Hugo van Leeuwen
Van Laarhoven Websites