extracting mailbox info from active directory

I'm currently trying to extract info such as mailbox size and item count from all the users in the active directory.

So far I have used this code:

Code:

---

' This code lists the size of all mailboxes on the selected server.

' ------ SCRIPT CONFIGURATION ------
 strComputerName = "<serverName>"        ' e.g. "batman"
 
' ------ END CONFIGURATION ---------
  strE2K3WMIQuery = "winmgmts://" & strComputerName &_
    "/root/MicrosoftExchangeV2"
 
  ' Find each mailbox on the target server and report their
  ' item counts and sizes
  Set mboxList = GetObject(strE2K3WMIQuery).InstancesOf("Exchange_Mailbox")
 
  For each mailbox in mboxList
          strOutput = ""
          strOutput =  "Mailbox: " & mailbox.MailboxDisplayName & vbCRLF
    strOutput = strOutput &  "  " & mailbox.Size & "KB in " & mailbox.TotalItems &_
        " items" & vbCRLF
          WScript.Echo strOutput
  Next

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referenced from "http://techtasks.com/code/viewbookcode/1246"

I have replaced teh server name with my own server's name and so far, I get the error :

Code:

---

Error:Permission denied: 'GetObject'
Code: 800a0046

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Any help would be appreciated ><