.net core下，excel的cells对象没有value方法

新开一个项目，尝试用.net core来做，调用excel时，发现原来framework下正常运行的代码不好用了，具体表现为，cells对象没有value方法了，这是怎么回事，要怎样才读写用单元格的值？

前面一段，新建excel对象，打开文件都正常，遍历worksheets，获取worksheet名字也正常，在最后获取cells(1,1).value时出错了，Public member 'Value' on type 'Range' not found.

我项目是.net  5.0，引用的是Microsoft Office 16.0 Object Library。

            Dim EX As Excel.Application
        Dim BK As Excel.Workbook
        Try
            EX = New Excel.Application
            EX.Workbooks.Open(T_File.Text,, True)
            BK = EX.ActiveWorkbook
        Catch
            MessageBox.Show("Can not open file.")
            EX.Quit()
            EX = Nothing
            Exit Sub
        End Try

        Dim nn As New List(Of String)
        For Each bb As Excel.Worksheet In BK.Worksheets
            nn.Add(bb.Name)
        Next

        Dim aa As New Form_Select_Sheet
        aa.L_Month.DataSource = nn.ToArray
        aa.L_Week.DataSource = nn.ToArray
        aa.L_Month.SelectedItems.Clear()
        aa.L_Week.SelectedItems.Clear()
        aa.ShowDialog()
        '此处对话框为获取excel的sheet


        If aa.SheetWeekly <> "" Then
            Dim TT As Excel.Worksheet = BK.Worksheets(aa.SheetWeekly)
            MsgBox(TT.Cells(1, 1).Value)

        End If


        EX.Quit()
        EX = Nothing

试一下TT.Range("B1").Value