类型＆＃39; System.NullReferenceException＆＃39;的未处理异常发生在代码中

Question

我一直在收到类型＆System; No。发生此错误的错误。它指向＆＃34; Dim TheRange As Range = oSheet.Cells（1,1）.Value＆＃34; 我确实打破了，发现TheRange的价值不算什么......不确定我做错了什么，或者我看不到它的东西。

 Dim OExcel As New Excel.Application
    OExcel.Visible = False 'Put true if you want to see the excel application showing on the screen
    Dim oBook As Excel.Workbook = OExcel.Workbooks.Open("C:\Users\cpushpa\Desktop\test.xlsx")
    Dim oSheet As Excel.Worksheet = TryCast(oBook.Worksheets(1), Worksheet)
    Dim TheRange As Range = oSheet.Cells(1, 1).Value
    Dim Data As String = ""
    For TheColumn As Integer = 1 To TheRange.Columns.Count
        For TheRow As Integer = 1 To TheRange.Rows.Count
            Data &= CType(oSheet.Cells(TheRow, TheColumn), Range).Value.ToString & ","
        Next
        Data = Data.TrimEnd(","c) & vbCrLf
    Next
    oBook.Close()
    OExcel.Quit()
    System.Runtime.InteropServices.Marshal.ReleaseComObject(OExcel)
    Using FileWriter As IO.StreamWriter = IO.File.CreateText("C:\Users\cpushpa\Desktop\DataTextFile.txt")
        FileWriter.WriteLine(Data)
    End Using
    Process.Start("Notepad", "C:\Users\cpushpa\Desktop\DataTextFile.txt")