Inspired to a recent episode

The apprentice went to Zen Master and cried: "My program does not work! I read and re-read my source code, I tried to use debugger, I added a lot of debugging messages!"

The Zen Master spoke softly: "Observer disturbs phenomenon".
Then, he turned off the monitor, run the apprentice's program and turned on the monitor. The result was correct.

The apprentice gained enlightenment.