may be you have no filter declared in the web.xml
I have other filters from shale and MyFaces declared in my web.xml
Could one of them or their properties as mapping intervene in ajax4jsf filter ?
The earlier version of shale used to have bug that causes the problem of integration. However, I did not see about any conflict for long period of time.
Search the Internet for the proven web.xml declaration. If I remember correctly, MyFaces wiki has something like that.
The problem was the integration with Shale
I was using the 1.0.4 and changed to 1.0.3 as you said
It's working ok now