AD Windows Domain Failed to Login

Need your expert. I just bought a unit WD My Cloud EX 2 Ultra. I had setup the AD connected to my windows Domain. i’m able to see a list of domain users under Users folder. It’s mean the WD Cloud EX2 able to communicate and pull the windows domain users to WD. I had created a private folder(“NetDrive1”) and assign Read/Write permission to domain user A. When i go to my computer and create a map drive to that shared folder(“NetDrive1”), it prompt up credential username and password. the problem is, the login cannot accept my username and password. i tried user name:\A, password:xxx. it still failed to login!
Please advice. thanks.Following is my WD setting.

Hi songlip,

Maybe you should try contacting WD’s Technical Support about this.

To Contact WD for Technical Support