Do you have BIRT servlet defined in the web.xml file?
The definition would be similar to the following:
<servlet>
<servlet-name>JBoss BIRT Servlet</servlet-name>
<servlet-class>org.jboss.tools.birt.servlet.JBossBirtServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>JBoss BIRT Servlet</servlet-name>
<url-pattern>/embed</url-pattern>
</servlet-mapping>