Excel 2007 not recognizing simple functions even after correct libraries added.

I have an issue where by Excel 2007 users of my Excel 2003 automated workbook are receiving the attached error when the following macro is run.  

I add the following library to the References but continue to get the error.  Anyone have any idea what steps I may be missing.

Library VBA:
    C:\Program Files\Common Files\Microsoft Shared\VBA\VBA6\VBE6.DLL
    Visual Basic For Applications

Public Sub VersionInfo()

'Macro to display the document version history

    Dim varIgnore As Integer
    Const cnstFileName = "DGSS Workbook-Checklist.xls"
    Const cnstCreated = "01-May-2010"
    Const cnstVersion = "2.1"
    Const cnstModified = "04-June-2010"

    varIgnore = MsgBox("File:   " & cnstFileName & Chr(13) & "Created:" & Chr(9) & cnstCreated & Chr(13) & "Modified:" & Chr(9) & cnstModified & Chr(13) & "Version:" & Chr(9) & cnstVersion, 64, cnstFileName)

End Sub

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Error-Msg.doc