Why web.xml does not work when I do not use a global namespace?

I have this very simple web.xml file:

<?xml version="1.0" encoding="UTF-8" ?>
<web-app xmlns="http://ift.tt/19L2NlC"
            xmlns:xsi="http://ift.tt/ra1lAU"
            xsi:schemaLocation="http://ift.tt/19L2NlC http://ift.tt/1drxgYl"
            version="3.1">
    <welcome-file-list>
        <welcome-file>testx.jsp</welcome-file>
    </welcome-file-list>
</web-app>

When I deploy the application and visit the context root, I will be taken to testx.jsp which is fine. But in my web.xml file I do not want to use a global namespace so I change the web.xml as follows:

<?xml version="1.0" encoding="UTF-8" ?>
<ee:web-app xmlns:ee="http://ift.tt/19L2NlC"
            xmlns:xsi="http://ift.tt/ra1lAU"
            xsi:schemaLocation="http://ift.tt/19L2NlC http://ift.tt/1drxgYl"
            version="3.1">
    <ee:welcome-file-list>
        <ee:welcome-file>testx.jsp</ee:welcome-file>
    </ee:welcome-file-list>    
</ee:web-app>

Now when I again start tomcat and visit the page, I will find myself in /index instead of /testx.jsp. But why?