oShell.run query

Hi all

Go easy on me - trying to make move from batch to *.vbs. It's going ....ok.... so far. Most of the *vbs is working except:

Dim oShell
Set oShell = WScript.CreateObject ("WScript.Shell")
oShell.run "ren c:\backup\*.btt ABC1.xml"
Set oShell = Nothing

ren c:\backup\*.btt ABC1.xml

from a CMD line it works fine... if I run the *.vbs I get "Line 3 Character 1 System cannot find file specified" 

What am I doing wrong?

Qaz