arduino uno + wifi shield + datalogger

Hello,

I use this shields:

https://www.arduino.cc/en/Main/ArduinoWiFiShield https://www.adafruit.com/product/1141

when i connect the three shields, (arduino uno + wifi shield + datalogger shield) the wifi shield is not recognized, but if i remove datalogger shield it works... I don't understand SPI protocol, i think i need that. Can someone explain to me how i solve my probleme?

Thank you so much!