problem connecting Arduino Ethernet Shield with Spartan 6

[javad_habibi]

Hi every one
I am trying to connect a spartan 6 board to an arduino ethernet shield. I have connected the ICSP Port of ethernet shield (MISO/SCK/RST/+5/MOSI/GND) to my FPGA board and a line of wire from pin 10 of ethernet shield(SS) to my FPGA board. That's all of my arduino ethernet shield connections.
But i cannot find out why my MISO feedback during write operation is once true and once not, as you see in the picture.(MISO should be 0X00 0X01 0X02 0X03 according to 6.3.3 part of w5100 datasheet).

• signals up to down in scope capture are:
  SCK(not visible because of sample frequency)
  MOSI
  MISO
  SS