Asp.net 从DDL中选择值时出错

我有

datalist

和

ddl

，用户可以从

ddl

中选择值绑定

datalist

。当用户选择值时，我试图在

datalist

中查找

ddl

时，出现了此错误

索引超出范围。必须是 非负数且小于 收藏。参数名称：索引

这里

所以请任何人帮助我

private DropDownList DDLProduct2;

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            ProductByProductID();
            CategoryParentZero();


        }
    }
 protected void DDlProduct_SelectedIndexChanged(object sender, EventArgs e)
    {
        DDLProduct2 = (DropDownList)DLProduct.Items[DLProduct.EditItemIndex].FindControl("DDlProduct");
        if (DDLProduct2 != null)
        {
            if (DDLProduct2.SelectedIndex > 0)
            {
                using
                (SqlConnection conn = Connection.GetConnection())
                {
                    SqlCommand cmd = new SqlCommand();
                    cmd.Connection = conn;
                    cmd.CommandType = CommandType.StoredProcedure;
                    cmd.CommandText = "SP_GetProductsByProductID";
                    SqlParameter ParentID_Param = cmd.Parameters.Add("@ProductID", SqlDbType.Int);
                    ParentID_Param.Value = DDLProduct2.SelectedValue;
                    ;
                    DataTable dt = new DataTable();
                    SqlDataAdapter da = new SqlDataAdapter();
                    da.SelectCommand = cmd;
                    da.Fill(dt);
                    DLProduct.DataSource = dt;
                    DLProduct.DataBind();

                }
            }
        }

    } 

---

DLProduct.EditItemIndex应等于-1，因为未编辑任何内容

如果DLProduct.EditItemIndex>=0，只需在抛出错误的行之前添加一个

private DropDownList DDLProduct2;

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            ProductByProductID();
            CategoryParentZero();


        }
    }
 protected void DDlProduct_SelectedIndexChanged(object sender, EventArgs e)
    {
        DDLProduct2 = (DropDownList)DLProduct.Items[DLProduct.EditItemIndex].FindControl("DDlProduct");
        if (DDLProduct2 != null)
        {
            if (DDLProduct2.SelectedIndex > 0)
            {
                using
                (SqlConnection conn = Connection.GetConnection())
                {
                    SqlCommand cmd = new SqlCommand();
                    cmd.Connection = conn;
                    cmd.CommandType = CommandType.StoredProcedure;
                    cmd.CommandText = "SP_GetProductsByProductID";
                    SqlParameter ParentID_Param = cmd.Parameters.Add("@ProductID", SqlDbType.Int);
                    ParentID_Param.Value = DDLProduct2.SelectedValue;
                    ;
                    DataTable dt = new DataTable();
                    SqlDataAdapter da = new SqlDataAdapter();
                    da.SelectCommand = cmd;
                    da.Fill(dt);
                    DLProduct.DataSource = dt;
                    DLProduct.DataBind();

                }
            }
        }

    }