I solved adding this:
<!-- MessageBroker Servlet -->
I have searched everywhere in the net to resolve this problem and finally i found the solution , of course it appear so easy like always, all what you have to do is to replace the context root in the properties of the flex project with the name of the project (/flex_name_project), normally you will find "/Webcontent", u have to replace it with the new one, and it's done
hope that will help you
I ran into same issue and although serverContextRoot was pointing to correct context .. follwoign was issue
--By default <servlet-class>flex.messaging.MessageBrokerServlet<\servlet-clas\> is declared with <\load-on-startup\>1<\/load-on-startup\>.
In my case i had changed <\load-on-startup\>1<\/load-on-startup\> to some other servlet ..and ran in this issue ..Conclusion <\load-on-startup\>1<\/load-on-startup\> MUST be used with <\servlet-class\>flex.messaging.MessageBrokerServlet<\/servlet-class\> It's NOT OPTIONAL