Deployment Error: Web AS 6.4 Preview

I'm trying to deploy an existing application EAR using deployTool

which contains a JAR and a WAR file. In the ejb-jar.xml I have the text shown below:

<message-driven >

<description><![CDATA[Cleanup TPX Service]]></description>

<display-name>CleanupMDBService</display-name>

<ejb-name>CleanupMDBService</ejb-name>

<ejb-class>com.clearorbit.connect.service.mdb.CleanupMDBService</ejb-class>

<transaction-type>Container</transaction-type>

<acknowledge-mode>Auto-acknowledge</acknowledge-mode>

<message-driven-destination>

<destination-type>javax.jms.Queue</destination-type>

</message-driven-destination>

</message-driven>

When I try to deploy I get a parse error:

com.sap.engine.deploy.exceptions.BaseIOException: Cannot parse persistent.xml

or storage.xml for jar <path to jar here>

Reason: com.sap.engine.deploy.exceptions.BaseIOException: Cannot parse ejb-jar.xml for jar <path to jar here>

Reason: java.lang.ArrayIndexOutOfBoundsException: 2..

When I take the acknowledge-mode tag out

i.e. <acknowledge-mode>Auto-acknowledge</acknowledge-mode>, it deploys.

If I use the deploy tool's GUI

to set the acknowledge-mode for an MDB, it generates

the exact same XML code as I have in my existing ejb-jar.xml. Why can't deploytool parse this line?