Using GWTEventService in cross site GWT

[the.wizard]

Hello everyone,
I was having a trouble using GWTEventService ini my GWT application which is using a xs option (in gwt.xml file). So my GWT application is cross site application, that's why I enabled the xs option in gwt.xml. Now, after I tried it with GWTEventService (the hello world GWTEventService example), I get an error like this :

IE :
Webpage error details

User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.2; WOW64; Trident/4.0; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
Timestamp: Sun, 23 Jun 2013 07:48:22 UTC


Message: Exception thrown and not caught
Line: 1167
Char: 65
Code: 0
URI: http://devk-pc-005.devkds.devbz.local:8081/PushNotificationResearch/pushnotificationresearch/00AAC9FE68B4C121084A1175657FFD19.cache.js

Chrome :
Failed to load resource: the server responded with a status of 404 (Not Found)
http://dev-pc-005.dev.local:8081/PushNotificationResearch/pushnotificationresearch/gwteventserviceFailed to load resource: the server responded with a status of 404 (Not Found)
AAF566DECF74BD4C7230A95F81FE80C0.cache.js:1154Uncaught de.novanic.eventservice.client.event.RemoteEventServiceRuntimeException: Error on activating / initializing "de.novanic.eventservice.client.event.RemoteEventService"!

My questions is :
1. Is GWTEventService can be used in application that enabled cross site feature?
2. How to solve the above errors?

Thanks & Regards.