Everything work fine follow Stuart's instruction here https://github.com/stuartwdouglas/modcluster-example
but when I changed the root context of the app to "/" the load balancing did not work any more, but still you can access to individual server.
I experimented with different root context like "/test", "/root" and I found that, setting any root context for app is OK except "/" (blank)
Best Regards,
Chanras