为什么我这个backgroundWorker1里的方法不执行


        //导出数据
        private void btnExport_Click(object sender, EventArgs e)
        {
           
           SaveFileDialog sa = new SaveFileDialog();
           sa.Filter = "Excel 97-2003文档(*.xls)|*.xls|Excel 97-2007文档(*.xls)|*.xls";
            if(sa.ShowDialog()==DialogResult.Cancel)
            {
                return;
            }
            fileName = sa.FileName;
            btnExport.Enabled = false;            backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
            backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
        }        //完成后进行保存数据并杀掉对应的进程
        void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            complete();
            KillSpecialExcel();
        }
        //后台查询导出数据
        void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            ExportMethod();
        }