TlsSocket.EndSend() throws System.InvalidCastException

Hello,

I've run into the following issue: whenever I try to finalize an asynchronous send operation with TlsSocket.EndSend(), I get the following exception:

System.InvalidCastException: InvalidCastException

   at Rebex.Net.TlsSocket.EndSend(IAsyncResult asyncResult)

   at Infrastructure.Communication.SecureTcpClient.SendCallback(IAsyncResult result)

   at tlqh.fehz(Object dqv)

   at System.Threading.ThreadPool.WorkItem.doWork(Object o)

   at System.Threading.Timer.ring()

The code that provokes it looks something like this:

// start asynchronous operation
socket.BeginSend(buffer, 0, buffer.Length, SocketFlags.None, SendCallback, socket);

// ... some lines skipped
private void SendCallback(IAsyncResult result)
{
    TlsSocket socket = (TlsSocket) result.AsyncState;

    socket.EndSend(result);

    //... further processing 
}

I'm using the latest 2018 R1 version of the library under .NET Compact Framework 3.5 on Windows CE.

Could you please help me to solve this issue?
Thanks in advance.