Some time ago I created a calendar to share it with the members of the department where I work. The problem is that one of the members can't categorized the events as we have determined. The buttons to create and delete are grey and therefore, nothing can be change. She can do this in her personal calendar but not in the shared one.
I've checked that she has all the permissions available and my IT staff has created one and shared with her and it works so we don't know which the problem can be.