Robot cant do runas in command line

runas error

I’m trying to let robot to type the password for the runas command in command line

Firstly robot will prompt an input dialog and let user enter password, then save it to a string variable

Then robot will open command line, type the runas command, then enter the string variable

But it would never get through, always says The user name or password is incorrect
Any thoughts?

Can you let me know if you got the same issue when you give the password as empty?