the remote server returned an error (550) file unavailable (e.g. file not found no access). ftp c#

public string[] ReadBOMFileList()
{
    string[] mydownloadFiles;
    StringBuilder myresult = new StringBuilder();
    //WebResponse myresponse = null;
    StreamReader myreader = null;
    FtpWebRequest myreqFTP = null;

    try
    {
        FTPSettings.IP = "abc.com/Project/TXN_BAAN/3DS_BOM";
        FTPSettings.UserID = "abc";
        FTPSettings.Password = "abc";
        myreqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + FTPSettings.IP + "/"));
        myreqFTP.Method = WebRequestMethods.Ftp.ListDirectory;
        myreqFTP.UseBinary = true;
        myreqFTP.Credentials = new NetworkCredential(FTPSettings.UserID, FTPSettings.Password);
        FtpWebResponse response = (FtpWebResponse)myreqFTP.GetResponse();
        myreader = new StreamReader(response.GetResponseStream());
        string myline = myreader.ReadLine();
        while (myline != null)
        {
            myresult.Append(myline);
            myresult.Append("\n");
            myline = myreader.ReadLine();
        }
        // to remove the trailing '\n'
        myresult.Remove(myresult.ToString().LastIndexOf('\n'), 1);
        return myresult.ToString().Split('\n');
    }
    catch (Exception ex)
    {
        if (myreader != null)
        {
            myreader.Close();
        }
        mydownloadFiles = null;
        return mydownloadFiles;
    }
}

private void DownloadBOMFile(string file)
{
    try
    {
        FTPSettings.IP = "abc.com/Project/TXN_BAAN";
        FTPSettings.UserID = "abc";
        FTPSettings.Password = "abc";
        string uri = "ftp://" + FTPSettings.IP + "/" + "3DS_BOM" + "/" + file;
        Uri serverUri = new Uri(uri);
        if (serverUri.Scheme != Uri.UriSchemeFtp)
        {
            return;
        }
        FtpWebRequest reqFTP;
        reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + FTPSettings.IP + "/" + "3DS_BOM" + "/" + file));
        reqFTP.Credentials = new NetworkCredential(FTPSettings.UserID, FTPSettings.Password);
        reqFTP.KeepAlive = false;
        reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;
        reqFTP.UseBinary = true;
        reqFTP.Proxy = null;
        reqFTP.UsePassive = false;
        FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
        Stream responseStream = response.GetResponseStream();
        if (!Directory.Exists(@"C:\AdminDB3DS_BOM"))
            Directory.CreateDirectory(@"C:\AdminDB3DS_BOM");
        FileStream writeStream = new FileStream(@"C:\AdminDB3DS_BOM\" + file, FileMode.Create);

        int Length = 2048;
        Byte[] buffer = new Byte[Length];
        int bytesRead = responseStream.Read(buffer, 0, Length);
        while (bytesRead > 0)
        {
            writeStream.Write(buffer, 0, bytesRead);
            bytesRead = responseStream.Read(buffer, 0, Length);
        }
        writeStream.Close();
        response.Close();
    }
    catch (WebException wEx)
    {
        TraceService(wEx.Message.ToString());
    }
    catch (Exception ex)
    {
        TraceService(ex.Message.ToString());
    }
}

public static class FTPSettings
{
    public static string IP { get; set; }
    public static string UserID { get; set; }
    public static string Password { get; set; }
}

string[] BOMfiles = ReadBOMFileList();
foreach (string BOMfile in BOMfiles)
{
    DownloadBOMFile(BOMfile);
}