I download & run GWTDemo for LS Colosseo - using JavaScript client 6.0. I get an error:

com.google.gwt.core.client.JavaScriptException: (TypeError) @gwtdemo.client.LSGWTLightstreamerClient::createCl ient()([]): undefined is not a function

I use GWT 2.5.1, JRE7, devmode.

How to solve it? Thanks.