我想做一个下载功能但不知道怎么做?我直接给加连接到下载的路径,但是没有弹出下载的对话框,而是显示无法找到网页.请各位指点一下应该怎么做?最好有代码

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using
using System.Data.SqlClient;


public partial class download : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string id = Request.QueryString["id"];
        string sql = "select Accessory from mail where ID = +id";
        SqlConnection conn = Database.GetOpenDatabase();
        SqlCommand cmd = new SqlCommand(sql,conn);
        SqlDataAdapter da = new SqlDataAdapter();
        DataSet ds = new DataSet();
        da.SelectCommand = cmd;
        da.Fill(ds);
        if(ds.Tables[0].Rows.Count>0)
        {
            //string path = ds.Tables[0].Rows[0]["Accessory"].ToString();
            string path = "//download//jianli.doc";
            if (path != null)
            {
                FileDownloadByFullName(path);
            }
        }
    }
    public static void FileDownloadByFullName(string FullFileName)
    {
        FileInfo DownloadFile = new FileInfo(FullFileName);
        HttpContext.Current.Response.Clear();
        HttpContext.Current.Response.ClearHeaders();
        HttpContext.Current.Response.Buffer = false;
        HttpContext.Current.Response.ContentType = "application/octet-stream";
        HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(DownloadFile.FullName, System.Text.Encoding.ASCII));
        HttpContext.Current.Response.AppendHeader("Content-Length", DownloadFile.Length.ToString());
        HttpContext.Current.Response.WriteFile(DownloadFile.FullName);
        HttpContext.Current.Response.Flush();
        HttpContext.Current.Response.End();
    }  
}
但是老出现找不到路径,请帮忙看看