Whoes fault is this?

In recent days in the CCU of the hospital, every patient of a particular bed dies at sharp 11 o'clock on Sundays. This matter seems not to relate to the illness type and any other factor.
This problem was wondering the hospital staff and all of the other patients. Some people relate this to the metaphysic, some to an unknown mean ghost and other causes. Nobody knew why every patient of that individual bed dies at 11 on Sundays? To solve it, all of the hospital doctors made a meeting and started to study on it. After spending so many hours about it and trying to consider all aspects of this phenomenon, at last they decided to wait until the next Sunday and look what happens to the poor patient!
Some minutes before 11, they were there to watch this complete strange disaster. It was two minutes to 11 that Johnson, the Sunday part time hospital's dustman arrived there. He unplugged the life support system cable and plugged his vacuum cleaner and started his work!!!!!!!!!!