Calendar problems with inviting attendees

[Waterland]

In our company we invite each other for meetings. For some
reason if we invite our boss, the meeting does not show in
his calendar until he accepts. This leads to the problem
that our boss receivens multiple invitations for the same
time period (as we cannot see the other invitations).

The strange thing is that if the secretary invites the
boss on behalf of one of us, the meeting pops up in his
calendar as tentative and everyone can see that he has a
meeting but has not accepted yet.

How can we solve this problem, and get to the situation
that every invitation to our boss pops up in his calendar
as a busy time period before he accepts or declines.

Thanks