Short answer is it works if you use a Google account and doesn't work if you don't.
I tried many times using just the Asus account and got the "Command Failed" response every time. Tried with my Google address (after reading this thread) and it worked straight away.
Incidentally, I tried the Asus support but they replied:-
Not impressed!Dear Customer,
Thank you for contacting the Asus Technical Support Team.
As this is third party software we are not able to help you with your problem.
Iím very sorry for the inconvience.