Erro no web.xml

Olá

Estou tendo um problema que é o seguinte se meu web.xml contiver somente as linhas abaixo:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="[http://www.w3.org/2001/XMLSchema-instance](http://www.w3.org/2001/XMLSchema-instance)" [xmlns="http://java.sun.com/xml/ns/javaee"](xmlns=) xsi:schemaLocation="http://java.sun.com/xml/ns/javaee [http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"](http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd) id="WebApp_ID" version="3.0">

<display-name>MyCrud</display-name>

 <welcome-file-list>
 <welcome-file>index.jsp</welcome-file>

 </welcome-file-list>

Porém se acrescento mais linhas a aplicação não rodar mais

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="[http://www.w3.org/2001/XMLSchema-instance](http://www.w3.org/2001/XMLSchema-instance)" [xmlns="http://java.sun.com/xml/ns/javaee"](xmlns=) xsi:schemaLocation="http://java.sun.com/xml/ns/javaee [http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"](http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd) id="WebApp_ID" version="3.0">
<display-name>MyCrud</display-name>
<welcome-file-list>
 <welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<resource-ref>
 <description>My DataSource</description>
 <res-ref-name>jdbc/meucrud</res-ref-name>
 <res-type>javax.sql.DataSource</res-type>
 <res-auth>Container</res-auth>
</resource-ref>
<filter>
 <filter-name>ConnectionFilter</filter-name>
 <filter-class>com.meucrud.dao.utils.ConnectionFilter</filter-class>
</filter>
<filter-mapping>
 <filter-name>ConnectionFilter</filter-name>
 <url-pattern>/*</url-pattern>
</filter-mapping>

</web-app>

Alguém sabe o motivo ?