Windows 8 user.setpassword Access is denied

Hi,

Does anyone has an idea why the following scipt

Set objUser = GetObject("WinNT://CompName/UserName,User")
objUser.SetPassword "test123"

(under admin account, with disabled UAC) returns "Access is denied" (80070005) error (on line 2, naturally) on Windows 8(.1) and Server 2012, while it works on Windows 7, Server 2008 R2 and XP?

Thanks in advance!