Hi, I verified there is no conflict in classloading the driver, I have one driver(10g) in the application lib. This is my ds.xml, Thanks! <xa-datasource> <jndi-name>XAOracleDS</jndi-name> <track-connection-by-tx/> <isSameRM-override-value>false</isSameRM-override-value> <xa-datasource-class>oracle.jdbc.xa.client.OracleXADataSource</xa-datasource-class> <xa-datasource-property name="URL">jdbc:oracle:thin:@x.x.x.x:1521:x</xa-datasource-property> <xa-datasource-property name="User">x</xa-datasource-property> <xa-datasource-property name="Password">x</xa-datasource-property> <!-- Uses the pingDatabase method to check a connection is still valid before handing it out from the pool --> <!--valid-connection-checker-class-name>org.jboss.resource.adapter.jdbc.vendor.OracleValidConnectionChecker</valid-connection-checker-class-name--> <!-- Checks the Oracle error codes and messages for fatal errors --> <exception-sorter-class-name>org.jboss.resource.adapter.jdbc.vendor.OracleExceptionSorter</exception-sorter-class-name> <!-- Oracles XA datasource cannot reuse a connection outside a transaction once enlisted in a global transaction and vice-versa --> <no-tx-separate-pools/> <!-- corresponding type-mapping in the standardjbosscmp-jdbc.xml (optional) --> <type-mapping>Oracle9i</type-mapping> </xa-datasource> <depends optional-attribute-name="TransactionManagerService">jboss:service=TransactionManager View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4008978#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...