我属于菜鸟级的，请大家多多包涵！
类VisitCheckStuHomeworks中s_SelectTeacherSubject是我写的一个查询方法

protected void g_SelectHomeworks_DataBound(object sender, EventArgs e)
    {
        DropDownList dl = (DropDownList)this.g_SelectHomeworks.Rows[0].FindControl("DropDownList2");
        int tid = 1;
        DataSet ds1 = VisitCheckStuHomeworks.s_SelectTeacherSubject(tid);
        string name = ds1.Tables[0].Columns[1].ToString();
        string id = ds1.Tables[0].Columns[0].ToString();
        dl.DataSource = ds1.Tables[0].DefaultView;
        dl.DataTextField = Eval("name").ToString();
        dl.DataValueField = Eval("id").ToString();
        dl.DataBind();
    }

那样我也试了，还是提示错误！未将对象应用到对象设置里，大概就是这个意思