The IE team has been trying to retire VBScript for years.
http://msdn.microsoft.com/en-us/library/windows/apps/Hh700404.aspx indicates that support was removed from the ExecScript API. http://msdn.microsoft.com/en-us/library/ie/dn384057(v=vs.85).aspx explains that it’s removed from IE11 Edge mode in the Internet Zone.
If you add the following to your HEAD tag, your VBScript will run:
<meta http-equiv="x-ua-compatible" content="IE=10">