Action "copy to personal calendar"

[praymond]

We have a shared calendar where we store general
events/meetings. It seems that I am able to copy some of
them to my own calendar using the "copy to personal
calendar" function but some of them I get the message
that I do not have the permissions.(bla bla bla)

What is different in those message that I can not copy
from the one I can.

Any help would be greatly appreciated

Thank you in advance