ADAU1761 problems on Zedboard

I am using the Avnet Zedboard,the controlling unit is ZYNQ(Xilinx FPGA+ARM),there is a ADAU1761 on this board. Now the FPGA have generated the I2S timing,the ARM have configured the chip by I2C,and generated a tested music data in ARM,the I2C works well,the I2S timing is OK too,but there is nothing sound in the speaker,can you give me some suggestions?

Thank you very much!