哪位大神看看下面这段代码有什么有关问题？代码没有异常，运行时出现有关问题，本人初学者勿喷

哪位大神看看下面这段代码有什么问题？代码没有错误，运行时出现问题，本人菜鸟勿喷！
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Reflection;
using  Excel=Microsoft.Office.Interop.Excel;

namespace 窗体
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Graphics g = Coordinate.GetCoordinate(panel1.CreateGraphics());//这里调用了一个Coordinate类文件，具体代码没写
        }
        float[,] y = new float[10, 2];
        float[]w = new float[10];
        PointF[]points = new PointF[10];
        private void button1_Click(object sender, EventArgs e)
        {
            OpenFileDialog fr= new OpenFileDialog();
            string filename="";
            fr.Filter = "xls文件|*.xls";         
            fr.RestoreDirectory = true;
            if (fr.ShowDialog() == DialogResult.OK)
            {
                filename = fr.FileName;
            }
            if (filename != "")
            {
                try
                {
                    Excel.Application xApp = new Excel.Application();
                    xApp.Visible = true;
                    Excel.Workbook xBook;
                    Excel.Worksheet xSheet;
                    xBook = xApp.Workbooks.Open(@filename,
                        Missing.Value, Missing.Value, Missing.Value, Missing.Value,
                        Missing.Value, Missing.Value, Missing.Value, Missing.Value,
                        Missing.Value, Missing.Value, Missing.Value, Missing.Value);
                    xSheet = (Excel.Worksheet)xBook.Sheets[1];
                    for (int i = 0; i < 10; ++i)
                    {
                        for (int j = 0; j < 2; ++j)
                        {
                            Excel.Range reg = (Excel.Range)xSheet.Cells[i + 1, j + 1];
                            y[i,j] = Convert.ToSingle(reg.Value2.ToString());
                        }