error

[kingdomh55]

----9/23/2011 4:32:18 PM ----
Type: InvalidCastException
Source: MCDzienny_
Message: Specified cast is not valid.
Target: Load
Trace: at MCDzienny.Level.Load(String givenName, Byte phys, Boolean lavaSurv)

An error appears and nobody can't join my server please help me.

[kingdomh55]

----9/23/2011 6:36:23 PM ----
Type: NullReferenceException
Source: MCDzienny_
Message: Object reference not set to an instance of an object.
Target: SendMessage
Trace: at MCDzienny.Player.SendMessage(Byte id, String message)
at MCDzienny.Player.SendMessage(String message)
at MCDzienny.Player.HandleLogin(Byte[] message)
at MCDzienny.Player.HandleMessage(Byte[] buffer)