one of my professors last semester was a student under a man who was a student under Einstein.

He was relaying a story to us one time about Mr. Einstein. Einstein was going back to his room one day, and he couldn't get the door to open. He'd put the key in, and the key wouldn't even turn. He looked at the room number... 214... that's the right number. He tried a couple of keys, and none of them worked. He knew he was at the right room number though, and could not figure out why the door would not open.

Finally, a student walks up and sees him having trouble, and asks if he can be of assistance. The student goes through Mr. Einstein's keys, trying them all out, and he too finds that none of the keys work. He asks Einstein if he's sure he's got the right room. He looks up again... 214... yep... that's the right room number.

After about 20 minutes of the student and Dr. Einstein working to figure out what the deal is, they finally figure out the problem.

He was in the wrong building the whole time!