Primefaces push in linux

I have deployed 2 web applications which have the push (notification) functions. Firstly, I deploy the first app (PUSH_SERVER) and publish web service. When the web method is called, the notification will be push to the second application. My configuration for the second app is as below:

<context-param>
    <param-name>primefaces.PUSH_SERVER_URL</param-name>
    <param-value>myURL</param-value>
</context-param>

The strange thing is: The push runs really well in Windows. But when I deploy them in Linux, in the same server. The first app is still able to get the notification. However, when I open the second app, I get this error (from FireBug):

Websocket closed, reason: Connection was closed abnormally (that is, with no close frame being sent).
Websocket closed, wasClean: false
Websocket failed. Downgrading to Comet and resending

I'm really confusing about this error. Would you give me some suggests?