XMLSchema troubles in Word 2007 under Vista whis UAC On

[Software_Developer]

Hello.

I've got a trouble with installing XML schema to Schema Library for All Users.
This issue is only reproduces under Windows Vista whis User Account Control
(UAC) turned On with Administrators privileges. All works fine under Windows
XP and Vista with UAC Off.

Here is a simple sample:

Public Sub Test()
'XMLNamespaces.Add(Path, NamespaceURI, Alias, InstallForAllUsers)
Application.XMLNamespaces.Add "c:\MySchema.xsd", "urn:www.my.com",
"MySchema", True
End Sub

Running this in Word's Visual Basic Editor throws Run-time error '4120': Bad
parameter.

Please help.
Thanks.