I am not allowed to create or alter content

When I tried to enter this discussion I received a message that I am not allowed to enter or alter this content. What does that mean?

Why does calendar delete my events without my instruction? When a make an event in my calendar on the iPhone, the next time I look for it it has disappeared. And it is not duplicated on my other devices - iPad and Macbook - via iCloud as it should be. As I understand iCloud, everything should be cross-duplicated between all connected devices. They do not. Can anyone answer my problem? All devices are running latest versions of respective software.