c# - TcpListener won't acknowledge connections -

so writing simple client-server application. should send packet, wait receive packet, send 1 etc... problem is, recieves first packet, when start tcplistener in second iteration, gives me error:

no connection made because target machine actively refused 127.0.0.1:13

private void listenforconnections()     {         bool prejelpaket = false;          listener = new tcplistener(ipaddress, port);         listener.start();          while (!packetreceived)         {             try             {                 client = listener.accepttcpclient();                 listener.stop();                  networkstream = client.getstream();                 byte[] message = new byte[1024];                 networkstream.read(message, 0, message.length);                 networkstream.close();                  string strmessage = encoding.utf8.getstring(message);                 packetreceived= true;                 messagebox.show("received message: " + strmessage);                  client.close();             }             catch (exception ee)             {                 thlisten.join();             }         }     }      private void sendpacket(object pclient)     {         string message = "test message;          try         {             client = (tcpclient)pclient;             client.connect(ipaddress, port);             networkstream = client.getstream();             byte[] strmessage = encoding.utf8.getbytes(message);             networkstream.write(strmessage, 0, strmessage.length);                        networkstream.close();             client.close();         }         catch (exception ex)         {             messagebox.show(ex.tostring());         }     } 

create client / networkstream once. store them in property until finished sending , receiving. close , dispose. not stop / close connection between each iteration.