in a random mode

one day a little cute girl trying to use a computer in computer lab, the following is the conversation bout..

girl A:Hey,B how come i have press the button,there is still nothing display on the screen?
girl B: I also don't know what happen,mine also have the same problem,go and ask that lady over there
girl A:excuse me,can i ask why the screen still BLACK BLACK one?i pressed the keyboard already.

that gentle lady gave us a sweet smile saying,i know what is the problem,this is because you didn't TURN ON the button.

*tut*