EntityManager NullPointerException

Por favor,
Estou tentando um EJB3 simples, mas quando tento usar o EntityManager ele está vindo sempre null na linha 8 do GerenciarCliente .
Parece que a annotation não está injetando o que deveria.
Vou tentar expor o máximo de detalhes.
Me avisem se quiserem ver mais algum detalhe.
E desde já agradeço.

@Stateless
public class GerenciarCliente implements GerenciarClienteLocal{
	@PersistenceContext(unitName="MyPersistenceUnit") 
	private EntityManager em;
		
	public boolean inserir(Client cliente){
		boolean retorno = false;
		em.persist(cliente);
		return retorno;
	}
}

@Local
public interface GerenciarClienteLocal {
	public boolean inserir(Client cliente);
}

<?xml version="1.0" encoding="UTF-8"?>
<application id="Application_ID" 
			 version="5" 
			 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
			 xmlns="http://java.sun.com/xml/ns/javaee"
			 xmlns:application="http://java.sun.com/xml/ns/javaee/application_5.xsd"
			 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/application_5.xsd">								
								
	<description>descrição: primeiro ejb</description>
	<display-name>EARejb03</display-name>
	<module>
		<web id="ejb_03">
			<web-uri>ejb03.war</web-uri>
			<context-root>/ejb03</context-root>
		</web>
	</module>
</application>

<?xml version="1.0" encoding="UTF-8"?>  
<persistence xmlns="http://java.sun.com/xml/ns/persistence"   
			 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"   
			 xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" 
			 version="1.0">
	<persistence-unit name="MyPersistenceUnit">
		<jta-data-source>java:/MyPostgreDS</jta-data-source>

		<properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect"/> 
            <property name="hibernate.hbm2ddl.auto" value="update"/>
		</properties>
		
	</persistence-unit>
</persistence>

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
		 xmlns="http://java.sun.com/xml/ns/javaee"
		 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
		 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

	<display-name>ejb03</display-name>
	
	<servlet>
		<servlet-name>MyServlet01</servlet-name>
		<servlet-class>web.myservlets.MyServlet01</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>MyServlet01</servlet-name>
		<url-pattern>/MyServlet01</url-pattern>
	</servlet-mapping>
</web-app>

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