Installation process from CVS tagged release

I get the JAHIA_4_0_4 released tag of the jahia distribution.
I've runned the ant build script to an existing Tomcat installation.

--> I've started the tomcat (with the tomcat startup scripts, not with the jahia.sh)
--> I did the installation process : ok
-->I've started myjahiasite and done some things : ok

But I've an error, trying to insert a webapp in the home page.
Adding a webapp, I had the following problem : 

org.jahia.exceptions.JahiaException  :Can't access context /InfoNews_myjahiasite, Eroor getting request context /InfoNews_myjahiasite.


Any idea ?  Is missing some configuration in the Tomcat installation ?


Thank's a lot

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