ClassCastException: weblogic.jndi.Alias when using multiple
JNDI names

Weblogic 10 MP1 under Windows XP SP3, Sun JDK 1.5.0_14

I have specified specified multiple JNDI names for a datasource. When I'm trying
to use that datasource, a ClassCastException: weblogic.jndi.Alias is thrown. So
it seems that an instance of Alias is returned instead of a DataSource. What am
I doing wrong? I'm using toplink essentials as persistence provider.

Stack trace:
java.lang.ClassCastException: weblogic.jndi.Alias
	at
oracle.toplink.essentials.jndi.JNDIConnector.connect(JNDIConnector.java:129)
	at
oracle.toplink.essentials.sessions.DatasourceLogin.connectToDatasource(Datasourc
eLogin.java:184)
	at
oracle.toplink.essentials.internal.sessions.DatabaseSessionImpl.loginAndDetectDa
tasource(DatabaseSessionImpl.java:582)
	at
oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider.login(EntityMana
gerFactoryProvider.java:280)
	at
oracle.toplink.essentials.internal.ejb.cmp3.EntityManagerSetupImpl.deploy(Entity
ManagerSetupImpl.java:229)
	at
oracle.toplink.essentials.internal.ejb.cmp3.base.EntityManagerFactoryImpl.getSer
verSession(EntityManagerFactoryImpl.java:93)
	at
oracle.toplink.essentials.internal.ejb.cmp3.base.EntityManagerFactoryImpl.create
EntityManagerImpl(EntityManagerFactoryImpl.java:126)
	at
oracle.toplink.essentials.internal.ejb.cmp3.base.EntityManagerFactoryImpl.create
EntityManagerImpl(EntityManagerFactoryImpl.java:120)
	at oracle.toplink.essentials.internal.ejb.cmp3.EntityManagerFactoryImpl.