Give an example of a good decision that you made that resulted in a bad outcome

Please illustrate a right conclusion you have done after involving in a wrong doing .
( This is only one of answers)

Good decision resulted in a bad outcome
The lights in our office building always keep shining all night hours.I never observed it before when I did overtime job one night last July.There was only one person working in one office but the whole building include each floor,even the corridor and washing rooms were bright like daytime.What a waste!
So I turned off the main switch behind the door when I left the office building at 9 O'clock.I felt a little bit pride that I should be praised by my boss for saving the power energy.
The next morning I heard my colleagues discussing somthing when I arrived in my office.One guy told me that our boss had been bited by his dog and had to take an injection for several times,and he stored the drugs in his fridge in his office.The drugs needed to be stored in constant low temperature.He was so angry that the drugs could not be used anymore.He had to go the hospital one more time to get some new drugs before making injections.
I felt embarrassed and put my tail into my legs and kept silient all that morning.