[Zope] How to add properties? No Add button visible

I am unable to Add properties. When I look at the Zope book, there is an Add button available, but I don't see that in my environment. For example. under the root folder, properties tab, I have a Save Changes button, but no Add or Delete buttons. Does anyone have any suggestions as to why this is the case? Zope 2.8.7 Regards Cameron