Well my client libraries are version 5.0 build 1446.3 and my lightstream server is Lightstreamer Server version 4.0.1 build 1513.1.3. Why is this happening then?

Also i have overridden the onClientAlert functions but message is still popping:

Code:
page.context.setDomain(map['domain']);
page.context.setDebugAlertsOnClientError(false);
page.onClientAlert = function(code, errorMex) {}
page.onEngineCreation = function(engine) {
engine.onClientAlert = function(code, errorMex) {}	
engine.connection.setLSHost(map['host']);
engine.connection.setLSPort(map['port']);
engine.connection.setAdapterName(map['adapter_root']);
engine.changeStatus(map['engine_status']);	
engine.context.setDebugAlertsOnClientError(false);
}
page.bind();
page.createEngine("app", map['ls_home'], map['ls_session']);