DAC8775: DAC8775 REFOUT Works abnormal

Part Number:DAC8775

My customer used DAC8775 and found REFOUT abnormal, Enable REFOUT but the PIN output only 1.2V, Source 5V to REFIN will bring down system power supply voltage. SPI bus read  and write operation works okay. the SPI code configuration is as below,  the customer want to know whether the hardware or software fault. 

 SPIWrite(0x01, 0x0001);//Software Reset

 SPIWrite(0x02, 0x0012);//Enable Reference, Power-off Condition, change to High-Z for VOUT and IOUT

 SPIWrite(0x03, 0x0020);//Select DAC Channel A 

 SPIWrite(0x04, 0x000F);// set for 4 to 20mA range 

 SPIWrite(0x04, 0x100F);//Enable output

 SPIWrite(0x05, 0x8000);//Write DAC Data Register value to mid-scale