更新已有内容时提示 对象必须实现 IConvertible

Question

 protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            ((DropDownList)this.FormView1.FindControl("DropDownList1")).Items.Clear();
            ((DropDownList)this.FormView1.FindControl("DropDownList6")).Items.Clear();            int k = 0;
            for (k = 0; k < 24; k++)
            {
                ((DropDownList)this.FormView1.FindControl("DropDownList1")).Items.Add(k.ToString());
                ((DropDownList)this.FormView1.FindControl("DropDownList6")).Items.Add(k.ToString());
            }
            ((DropDownList)this.FormView1.FindControl("DropDownList2")).Items.Clear();
            ((DropDownList)this.FormView1.FindControl("DropDownList7")).Items.Clear();            int r = 0;
            for (r = 0; r < 60; r++)
            {
                ((DropDownList)this.FormView1.FindControl("DropDownList2")).Items.Add(r.ToString());
                ((DropDownList)this.FormView1.FindControl("DropDownList7")).Items.Add(r.ToString());
            }            ((LinkButton)this.FormView1.FindControl("InsertButton")).Attributes.Add("onclick", "javascript:if(confirm('确定要添加吗?')){}else{return false;}");
        }
    }
    protected void InsertButton_Click(object sender, EventArgs e)
    {
        //插入日期
        ((HiddenField)this.FormView1.FindControl("HiddenField1")).Value = ((Meta.Web.Controls.DropDownCalendar)this.FormView1.FindControl("FreeDate")).Value.ToString("d");
        //插入录入人员
        ((HiddenField)this.FormView1.FindControl("SerPerson")).Value = Session["StaffName"].ToString();
        // 插入录入时间;
        ((HiddenField)this.FormView1.FindControl("SerDate")).Value = DateTime.Now.ToString();
        //插入各起止时间
        ((HiddenField)this.FormView1.FindControl("FreeTime")).Value = (((DropDownList)this.FormView1.FindControl("DropDownList1")).Text) + "：" + (((DropDownList)this.FormView1.FindControl("DropDownList2")).Text);
        ((HiddenField)this.FormView1.FindControl("OutTime")).Value = (((DropDownList)this.FormView1.FindControl("DropDownList6")).Text) + "：" + (((DropDownList)this.FormView1.FindControl("DropDownList7")).Text);
    }
这些就是编辑页面的代码。麻烦看一下有没有错误！

Answer 1

对protected void InsertButton_Click(object sender, EventArgs e) 
里面的代码中设置断点，看看执行到哪里就会出现问题。用个try  catch 来捕获该异常。