Because on the Arduino Mega pins 10--13 are not the hardware SPI which are on pins 50--53 instead. The ICSP header gets the hardware SPI pins whichever board. General purpose shields using SPI use the ICSP header for this reason
Because on the Arduino Mega pins 10--13 are not the hardware SPI which are on pins 50--53 instead. The ICSP header gets the hardware SPI pins whichever board. General purpose shields using SPI use the ICSP header for this reason