Matlab camera calibration getting peripheral corners

I don't know why, but Matlab Camera Calibration app is getting also the peripheral corners, it is not supposed to do that. Any clues?

By the way, the border squares are more thinner by purpose, just to try to make Matlab ignore them, I also used normal squares side on the borders but I got the same Matlab behavior.

My image result: <http://i.stack.imgur.com/sUHbg.png>

Correct result from matlab website: <http://i.stack.imgur.com/iZFWK.png>