I'm tring to run a vb script on the command line and I get this error :

Srcipt: xyz.vbs
Line: 98
Char: 1
Error: Variable is undefined: 'oShell'
Code: 800A01F4
Source: Microsoft VBScript runtime error

and this is the code on line 98:

Set oShell = CreateObject("WScript.Shell")

Do I have to define a variable for oShell ?
What I'm doing wrong ?

Any help is realy apreciate.