C#读取excel，行数问题

从excel（有三行数据）读出数据填充到dataset中，为什么count总是显示只有2行（实际应该为3行）
private void toolStripButton7_Click(object sender, EventArgs e)
        {
            OpenFileDialog open = new OpenFileDialog();
            open.Filter = "Excel files (*.xls)|*.xls";
            open.DefaultExt = "xls";
            //open.FileName = "*.xls";
            open.Title = "要导入的EXCEL文件";
            if (open.ShowDialog() != DialogResult.OK)
                return;
            string opnFileName = open.FileName;
            string strConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + opnFileName + ";Extended Properties=\"Excel 8.0;HDR=YES;IMEX=1\"";
            try
            {
                OleDbConnection myConn = new OleDbConnection(strConn);
                string strCom = " SELECT * FROM [Sheet1$]";                myConn.Open();
                OleDbDataAdapter myCommand = new OleDbDataAdapter(strCom, myConn);
                DataSet ds = new DataSet();
                if (ds.Tables.Contains("TAB1"))
                {
                    ds.Tables.RemoveAt(ds.Tables.IndexOf("TAB1"));
                }
                myCommand.Fill(ds, "TAB1");
                int count = ds.Tables["TAB1"].Rows.Count;//这里取出的行数总是比实际的少一行
                myConn.Close();
                myConn.Dispose();
            }
}