Looking through file names for a duplicate

I tried the following. I can't understand why nothing is written at labelb

<code>
        Dim file_name As String
        Dim FolderAddr As String = HttpContext.Current.Server.MapPath("Smith")
        ' For example on test : FolderAddr = d:\websites\xxxyyy\wwwroot\Smith
        Dim DirInfo As New DirectoryInfo(FolderAddr)
        '      
        For Each FileInfo In DirInfo.GetFiles
            file_name = FileInfo.FullName
            Labelb.Text = "File_name = " & file_name ' Nothing written at labelb
        Next

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