6) You could have notified me in time that you would not come.
7) He might have not found the address, and therefore has not yet written to you.
8) Wait for me, if I am not here at seven. I can be late for a few minutes.
9) You might not have wanted to offend him, but in fact you did. He must not have understood you properly.
10) Apparently, you might not have been careful enough. Nobody might have warned you that it could happen.