VBA vault UndoCheckoutTop only working once?

[Anonymous]

I have written a macro to open and look through drawings in inventor. I would like it to UndoVaultCheckoutTop for certain drawings which do not require changing however my macro will only undocheckout for the first drawing and does not work the for the subsequent drawings.

Here is a shortened version of code containing the important part.

    Dim oDoc As Document
    For Each oDoc In ThisApplication.Documents.VisibleDocuments
        If oDoc.DocumentType = kDrawingDocumentObject Then
            oDoc.Activate
            ''Sub to look through the drawing
        End If
    Next

''In the sub that looks through the drawing
''If unchanged then
            Set ctrdef = ThisApplication.CommandManager.ControlDefinitions.Item("VaultUndoCheckoutTop")
            ctrdef.Execute
            DoEvents
            invDoc.Close (True)
            DoEvents
''End if 

Each document that is unchanged does get here and is closed as it should be however only the first one has the checkout undone. The rest are closed but remain checked out. Is there any reason that this happens/ how can I fix this?

Thank you.