C＃Interop.Excel-空范围对象异常

Question

由于某种原因，我无法使用C＃的Interop.Excel库检索单元格的值。尝试访问Range对象的.Value属性时，出现了空引用异常。有问题的工作表在我定位的单元格中肯定有一个值。有小费吗？请参见下面的代码：

using System;
using System.Data;
using System.Collections.Generic;
using Microsoft.Office.Interop.Excel;

namespace C__Test
{
    class Program
    {
        static void Main(string[] args)
        {
            Application xlApp = new Application();
            xlApp.DisplayAlerts = false;
            xlApp.ScreenUpdating = false;
            xlApp.Visible = false;
            Workbook xlBook = xlApp.Workbooks.Open(@"C:\Users\tsgardn\Desktop\test.xlsb",Type.Missing,true);
            _Worksheet xlSheet = (_Worksheet)xlBook.Worksheets["Scorecard"];
            xlBook.RefreshAll();
            Range ranges = xlSheet.UsedRange;

            foreach (Range c in ranges.Cells) {
                Console.WriteLine("Address: " + c.Address + "Value: " + c.Value);
            }

            xlBook.SaveAs(@"C:\Users\tsgardn\Desktop\Corelogic Flood Scorecard - New.xlsb");
            xlBook.Close(false);
        }
    }
}