In fact, the problem is solved: I use the arduino mega 2560 and the SCK, MISO and MOSI pins are located on another header.
If you want to use this board, you must connect:
Mega Shield
51 11
50 12
52 13
You have also to replace the lines
pinMode(10, OUTPUT); //Pin 10 must be set as an output for the SPI communication to work: UNO
pinMode(53, OUTPUT); //Pin 53 must be set as an output for the SPI communication to work: MEGA
