Why is Communication so Difficult?

I was wondering why is difficult to communicate and idea or knowledge to other people, so I find this very nice paper on that:

Miscommunication as a Chance Theory, by Luigi Anolli. In this paper the author argues that miscommunication is part of the process because of 2 different schemas try to communicate with each other in a reference time.

Furthermore there is a lot of mental schemas we have to understand first in order to understand more complex ones.