WebSphere 7.0.0.13, JPA 1.0 - First component in name persistence/myPU not found

[a sarkar]

Stacktrace:

Caused by: javax.naming.NameNotFoundException: Context: MY_TEST/clusters/MY_DEV, name: persistence/myPU: First component in name persistence/myPU not found. [Root exception is org.omg.CosNaming.NamingContextPackage.NotFound: IDL:omg.org/CosNaming/NamingContext/NotFound:1.0]
	at com.ibm.ws.naming.jndicos.CNContextImpl.mapNotFoundException(CNContextImpl.java:4365)
	at com.ibm.ws.naming.jndicos.CNContextImpl.doLookup(CNContextImpl.java:1794)
	at com.ibm.ws.naming.jndicos.CNContextImpl.doLookup(CNContextImpl.java:1749)
	at com.ibm.ws.naming.jndicos.CNContextImpl.lookupExt(CNContextImpl.java:1500)
	at com.ibm.ws.naming.jndicos.CNContextImpl.lookup(CNContextImpl.java:637)
	at com.ibm.ws.naming.util.WsnInitCtx.lookup(WsnInitCtx.java:165)
	at com.ibm.ws.naming.util.WsnInitCtx.lookup(WsnInitCtx.java:179)
	at javax.naming.InitialContext.lookup(InitialContext.java:455)
	at org.springframework.jndi.JndiTemplate$1.doInContext(JndiTemplate.java:154)

persistence.xml:

<jta-data-source>jdbc/MY_DEV</jta-data-source>
<properties>
	<property name="hibernate.hbm2ddl.auto" value="validate" />
	<property name="hibernate.show_sql" value="false" />
	<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
	<property name="transaction.factory_class"
		value="org.hibernate.transaction.JTATransactionFactory" />
	<property name="transaction.manager_lookup_class"
		value="org.hibernate.transaction.JBossTransactionManagerLookup" />
</properties>

web.xml:

<persistence-context-ref>
	<persistence-context-ref-name>persistence/myPU</persistence-context-ref-name>
	<persistence-unit-name>myPU</persistence-unit-name>
	<persistence-context-type>Transaction</persistence-context-type>
</persistence-context-ref>

[a sarkar]

Please help.