There are many possible reasons as to why you were not able to set the device output.
Please refer to this FAQs: FAQs: DAC Communication Troubleshooting
1) One way is also to use readback command to check whether your communication interface is good.
2) For AD5761, please take note of this:
3) What commands did you send after the device was powered?
Please let me know if you were able to check on those things.