Hello Yana,
Can you enable the client logger and send the output to
support@lightstreamer.com?
You can enable the logger by adding the following lines to your application:
var log = new SimpleLoggerProvider();
log.addLoggerAppender(new ConsoleAppender("DEBUG", "*"));
LightstreamerClient.setLoggerProvider(log);
Which server version are you using?
Are you using a single Lightstreamer server or a cluster behind a load balancer?
Have you configured a control link address for your Lightstreamer server?
Regards