Problem for "System.Net.Sockets.SocketException: No connection could be made because the target machine actively refused it 127.0.0.1:64855"

Question

I faced the problem about the Socket. When i need to pass my username and password into the web service, the 
system give me this error "System.Net.Sockets.SocketException: No connection could be made because the target machine actively refused it 127.0.0.1:64855"

Line 32: TestWService.TestWebService ws = new TestWService.TestWebService();
Line 33: string a = ws.Login(txtUsername.Text, txtPassword.Text);

i had tried many things that post in the websites, still cannot solve this problem..
could anyone help me..?
thanks.