I'm able to connect using SFTP but when I send login credentials I am receiving an error? Any ideas?

The Log:

2010-09-01 11:08:21.687 Opening log file.
2010-09-01 11:08:21.875 ERROR Sftp(5) Info: Rebex.Net.SshException: Received invalid packet.
   at wWGvS.AIchsYZ.AcUJKJ(Byte[] )
   at Rebex.Net.SshSession.AePCoRZ(Byte[]& )
   at Rebex.Net.SshSession.cDtmAOZ(Int64& , Boolean )
   at Rebex.Net.SshSession.CFLiXJ(ANiLIV )
   at Rebex.Net.SshSession.CgoKrJZ()
   at Rebex.Net.SshSession.cCIjvV(String , String , SshPrivateKey , SshGssApiCredentials )
   at Rebex.Net.SshSession.Authenticate(String userName, String password, SshPrivateKey privateKey)
   at Rebex.Net.Sftp.Login(String userName, String password, SshPrivateKey privateKey)
2010-09-01 11:10:50.046 Opening log file.
2010-09-01 11:10:50.046 INFO Sftp(7) Info: Connecting to www.xyz.com:22 using Sftp 2.0.3854.0 (trial version).
2010-09-01 11:10:50.265 DEBUG Sftp(7) SSH: Server is 'SSH-2.0-OpenSSH_4.3'.
2010-09-01 11:10:50.265 DEBUG Sftp(7) SSH: Negotiation started.
2010-09-01 11:10:50.328 DEBUG Sftp(7) SSH: Group exchange.
2010-09-01 11:10:50.406 DEBUG Sftp(7) SSH: Negotiating key.
2010-09-01 11:10:51.343 DEBUG Sftp(7) SSH: Validating signature.
2010-09-01 11:10:51.359 DEBUG Sftp(7) SSH: Negotiation finished.
2010-09-01 11:10:51.359 INFO Sftp(7) Info: Server: SSH-2.0-OpenSSH_4.3
2010-09-01 11:10:51.359 INFO Sftp(7) Info: Fingerprint: d7:f3:65:20:ad:9c:3c:23:0e:cd:d4:d3:32:a9:42:c3
2010-09-01 11:10:51.359 INFO Sftp(7) Info: Cipher info: SSH 2.0, DiffieHellmanGroupExchangeSHA1, DSS, aes256-ctr/aes256-ctr, SHA1/SHA1

The Code:

    Sftp client = new Sftp();
    client.LogWriter = new Rebex.FileLogWriter(@"c:\work\log2.txt", Rebex.LogLevel.Debug); 
    // Create an instance of SshParameters class 
    // to specify desired arguments. 
    SshParameters par = new SshParameters();

    // Disable transfer compression 
    par.Compression = false;

    // Any key exchange method is acceptable. 
    par.KeyExchangeAlgorithms = SshKeyExchangeAlgorithm.DiffieHellmanGroupExchangeSHA1;

    // Only allow AES and 3DES encryption methods. 
    par.EncryptionAlgorithms = SshEncryptionAlgorithm.AES | SshEncryptionAlgorithm.TripleDES;

    // Connect to the server. 
    // The third argument refers to the parameters class. 
    client.Connect(FTPHost, Sftp.DefaultPort, par);



    // verify the server's fingerprint (client.Fingerprint) 

    SshPrivateKey privateKey = new SshPrivateKey(@"c://work/key_rsa.pem", "password");

    // authenticate 
    client.Login(FTPUser, privateKey);

    client.Disconnect();