Accessing with JPA

Has anyone successfully setup persistence with JPA?  Someone posted configuration for JDO (thanks!):

http://code.google.com/apis/sql/docs/google-cloud-sql-discuss.html?place=topic%2Fgoogle-cloud-sql-discuss%2FaUL1N-ASr6k%2Fdiscussion

But I've tried to do the same for JPA and am getting this error:

org.datanucleus.exceptions.NucleusUserException: There is no available StoreManager of type "rdbms". Please make sure you have specified "datanucleus.storeManagerType" correctly and that all relevant plugins are in the CLASSPATH

I'm using these DataNucleus references:

http://www.datanucleus.org/products/accessplatform/jpa/emf.html

http://www.datanucleus.org/products/accessplatform/persistence_properties.html

And here's the relevant part of my persistence.xml:

<persistence-unit name="pu-searchindex-1">

<provider>org.datanucleus.api.jpa.PersistenceProviderImpl</provider>

<properties>

<property name="javax.persistence.jdbc.driver" value="com.google.appengine.api.rdbms.AppEngineDriver"/>

<property name="datanucleus.ConnectionURL" value="jdbc:google:rdbms://commentous.com:web-prod:searchindex-1/ctssearchidx"/>

<property name="datanucleus.autoCreateTables" value="true"/>

<property name="datanucleus.storeManagerType" value="rdbms"/>

<property name="datanucleus.jpa.level" value="JPA1"/>

<property name="datanucleus.jpa.addClassTransformer" value="false"/>

</properties>

</persistence-unit>