How configure reconnecting in socket.io?

I create socket.io connection with next code

var socket = new io.connect('http://localhost:8181', {
    'reconnect': true,
    'reconnection delay': 500,
    'max reconnection attempts': 50
});

But when I kill server CTRL+C and start it again, reconnection isn't happening. But disconnect event raised on client side. What maybe reason of it?