访问网络文件时出现返回1203，请教解决原因！！！[

在做网络文件访问时总是返回1203错误，在开发服务器上执行\\121.74.2.118\share\能访问网络文件夹，
用net use \\121.74.2.118\share\ 也显示正常，其中用户guest正常
请教直接运行 net use \\121.74.2.118\share\  
能在计算机管理_系统工具_共享文件夹_会话中有联接信息
但是运行上面代码却没有联系到共享文件夹，也没有任何会话信息
其中:网络防火墙关于，两台计算机属于同一网段，访问正常
但是用下面两段代码都返回1203，请教解决原因！！！
下面代码using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.IO;
namespace SearchFileService
{
    public enum ERROR_ID
    {
        ERROR_SUCCESS = 0, // Success 
        ERROR_BUSY = 170,
        ERROR_MORE_DATA = 234,
        ERROR_NO_BROWSER_SERVERS_FOUND = 6118,
        ERROR_INVALID_LEVEL = 124,
        ERROR_ACCESS_DENIED = 5,
        ERROR_INVALID_PASSWORD = 86,
        ERROR_INVALID_PARAMETER = 87,
        ERROR_BAD_DEV_TYPE = 66,
        ERROR_NOT_ENOUGH_MEMORY = 8,
        ERROR_NETWORK_BUSY = 54,
        ERROR_BAD_NETPATH = 53,
        ERROR_NO_NETWORK = 1222,
        ERROR_INVALID_HANDLE_STATE = 1609,
        ERROR_EXTENDED_ERROR = 1208,
        ERROR_DEVICE_ALREADY_REMEMBERED = 1202,
        ERROR_NO_NET_OR_BAD_PATH = 1203
    }    public enum RESOURCE_SCOPE
    {
        RESOURCE_CONNECTED = 1,
        RESOURCE_GLOBALNET = 2,
        RESOURCE_REMEMBERED = 3,
        RESOURCE_RECENT = 4,
        RESOURCE_CONTEXT = 5
    }    public enum RESOURCE_TYPE
    {
        RESOURCETYPE_ANY = 0,
        RESOURCETYPE_DISK = 1,
        RESOURCETYPE_PRINT = 2,
        RESOURCETYPE_RESERVED = 8,
    }    public enum RESOURCE_USAGE
    {
        RESOURCEUSAGE_CONNECTABLE = 1,
        RESOURCEUSAGE_CONTAINER = 2,
        RESOURCEUSAGE_NOLOCALDEVICE = 4,
        RESOURCEUSAGE_SIBLING = 8,
        RESOURCEUSAGE_ATTACHED = 16,
        RESOURCEUSAGE_ALL = (RESOURCEUSAGE_CONNECTABLE | RESOURCEUSAGE_CONTAINER | RESOURCEUSAGE_ATTACHED),
    }    public enum RESOURCE_DISPLAYTYPE
    {
        RESOURCEDISPLAYTYPE_GENERIC = 0,
        RESOURCEDISPLAYTYPE_DOMAIN = 1,
        RESOURCEDISPLAYTYPE_SERVER = 2,
        RESOURCEDISPLAYTYPE_SHARE = 3,
        RESOURCEDISPLAYTYPE_FILE = 4,
        RESOURCEDISPLAYTYPE_GROUP = 5,
        RESOURCEDISPLAYTYPE_NETWORK = 6,
        RESOURCEDISPLAYTYPE_ROOT = 7,
        RESOURCEDISPLAYTYPE_SHAREADMIN = 8,
        RESOURCEDISPLAYTYPE_DIRECTORY = 9,
        RESOURCEDISPLAYTYPE_TREE = 10,
        RESOURCEDISPLAYTYPE_NDSCONTAINER = 11
    }    [StructLayout(LayoutKind.Sequential)]
    public struct NETRESOURCE
    {
        public RESOURCE_SCOPE dwScope;
        public RESOURCE_TYPE dwType;
        public RESOURCE_DISPLAYTYPE dwDisplayType;
        public RESOURCE_USAGE dwUsage;        [MarshalAs(UnmanagedType.LPStr)]
        public string lpLocalName;        [MarshalAs(UnmanagedType.LPStr)]
        public string lpRemoteName;        [MarshalAs(UnmanagedType.LPStr)]
        public string lpComment;        [MarshalAs(UnmanagedType.LPStr)]
        public string lpProvider;
    }    public class NetworkConnection
    {        [DllImport("mpr.dll")]
        public static extern int WNetAddConnection2A(NETRESOURCE[] lpNetResource, string lpPassword, string lpUserName, int dwFlags);        [DllImport("mpr.dll")]
        public static extern int WNetCancelConnection2A(string sharename, int dwFlags, int fForce);
        public static int Connect(string remotePath, string localPath, string username, string password)
        {
            NETRESOURCE[] share_driver = new NETRESOURCE[1];
            share_driver[0].dwScope = RESOURCE_SCOPE.RESOURCE_GLOBALNET;
            share_driver[0].dwType = RESOURCE_TYPE.RESOURCETYPE_DISK;
            share_driver[0].dwDisplayType = RESOURCE_DISPLAYTYPE.RESOURCEDISPLAYTYPE_SHARE;
            share_driver[0].dwUsage = RESOURCE_USAGE.RESOURCEUSAGE_CONNECTABLE;
            share_driver[0].lpLocalName = localPath;
            share_driver[0].lpRemoteName = remotePath;            Disconnect(localPath);
            int ret = WNetAddConnection2A(share_driver, password, username, 1);            return ret;
        }        public static int Disconnect(string localpath)
        {
            return WNetCancelConnection2A(localpath, 1, 1);
        }        public static bool CheckFile()
        {
            string localpath = "X:";
            //int status = NetworkConnection.Connect(@"\\192.168.0.2\test", localpath, @"test", "test");
            int status = NetworkConnection.Connect(@"\\121.74.2.118\share\", localpath, @"Guest", "");
            if (status == (int)ERROR_ID.ERROR_SUCCESS)
            {
                FileStream fs = new FileStream(localpath + @"\\1.txt", FileMode.OpenOrCreate);
                using (StreamWriter stream = new StreamWriter(fs))
                {
                    //stream.WriteLine("你好呀，成功了");
                    stream.Flush();
                    stream.Close();
                }
                fs.Close();
            }
            else
            {
                Console.WriteLine(status);
                return false;
            }
            NetworkConnection.Disconnect(localpath);
            return true;
        }    }
}