Change Theme VBS Not working... Thoughts?

I was asked to move this to scripting... Any help is appreciated.

This is the Script we use today for Windows 7, but this does not work for Windows 8 / 8.1.  When running it keeps bringing up the Desktop Icon Settings Box???

Set WshShell = WScript.CreateObject("WScript.Shell")

WshShell.Run "rundll32.exe %SystemRoot%\system32\shell32.dll,Control_RunDLL %SystemRoot%\system32\desk.cpl desk,@Themes /Action:OpenTheme /file:""ThemeLocation\MY.theme"""

Wscript.Sleep 1600
WshShell.AppActivate("Desktop Properties")
WshShell.Sendkeys "%FC"
WshShell.Sendkeys "{F4}"