because it seems that on mega the spi pin are different than the wiring of these chinese shield.
chinese shield
SS - mega pin 53
MOSI - mega pin 52
SCK - mega pin 51
MISO - mega pin 50
mega
this is 50 (MISO), 51 (MOSI), 52 (SCK), and 53 (SS). MISO, MOSI
I suppose the chineses do an error between sck and mosi ?