取GridView中文本框的值

我把文章在列表中按它们是否被加密码判断完显示哪个Panel了，然后就是在有密码的Panel中向TextBox输入密码，点击确认按钮，代码如下，问题是取不出来TextBox中的值，我的这两个Panel（有密码显示的和没密码显示的Panel）是直接放在GridView的ItemTemplate中的，Colunm0，我做了试验，Panel放在规律的列中，比如Colunm3中，我就用Cells[2]就能取出来，那我这种情况应该怎样处理呢？？？？
protected void btnCommit_Click(object sender, EventArgs e)
    {
        Button bt1 = sender as Button;
        if (() == "bb")
        {
            foreach (GridViewRow gr in GridView1.Rows)
            {
              TextBox tb = (TextBox)gr.Cells[0].FindControl("txtPass");      
                string pass = ();
                string password = tb.Text.Trim();
                Panel p1 = (Panel)gr.Cells[0].FindControl("pPassNone");
                Panel p2 = (Panel)gr.Cells[0].FindControl("pPass");
                if (password == pass)
                {
                    p1.Visible = true;
                    p2.Visible = false;
                }
            }
        }
    }