再次求助！asp.net引用外部DLL问题

我有个外部的ycode.dll，我在asp.net 中就是引用不了，弹出错误的对话框，说是找不到该dll。我在网上找了一大堆资料，也都试了，绝对路径，甚至放在系统system32 下面 都没有用。。
我把代码[贴出来，今天就在这等了，解决后立即结贴。。。
C# code:

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

using System.Runtime.InteropServices;
public partial class _Default : System.Web.UI.Page
{

[DllImport("ycode.dll", EntryPoint = "loadcode", SetLastError = true, ExactSpelling = false, CallingConvention = CallingConvention.StdCall)]
public static extern int loadcode(int i, int j, string str, string enjoy);
[DllImport("ycode.dll", EntryPoint = "Recognition")]
public static extern int Recognition(int i, int j, int a, string str, string enjoy, int b, int c, int d);

[DllImport("ycode.dll", EntryPoint = "Recognitiond")]
public static extern string Recognitiond(int i, int j, int a, string str, string enjoy);

[DllImport("ycode.dll", EntryPoint = "lstrcpy")]
public static extern int lstrcpy(string enjoy, int i);

[DllImport("