AD5560 0X8register question, load capacity

Hi 

I have two question need to help. 

1) When writing 0V to register 0x8, the output will be 0.75V, and the output will be 0.75V more when writing different voltages (equal to a bias voltage of 0.75V added). How to solve this situation ?

2) During debugging, the electronic load was used to test the gear of ±500mA and ± 1.2A, and we find that the load capacity could not be reached. it only can load about <350mA when select ±500mA range. and load <700mA when  ± 1.2A range at any volatge output . When the load beyond,  the AD5560 will be no output. how is that ?