ActiveBPEL Persistent Configuration won't start

environment:
tomcat 5.5.12
mysql 4.1
activebpel 2.1 (1473)

problem:
- activebel engine with persistent configuration won't start.

symptoms:

- activebpel status says:
Error: Storage not available, see storage page for details.

- tomcat logs say:
Jul 31, 2006 11:18:26 AM org.activebpel.rt.AeException logError
SEVERE: org.activebpel.rt.bpel.server.engine.storage.AeStorageException: Error initializing the persistent store factory.
at org.activebpel.rt.bpel.server.engine.storage.AePersistentStoreFactory.init(AePersistentStoreFactory.java:84)
at org.activebpel.rt.bpel.server.engine.AeEngineFactory.initializePersistentStoreFactory(AeEngineFactory.java:484)
at org.activebpel.rt.bpel.server.engine.AeEngineFactory.initializeStorage(AeEngineFactory.java:274)
at org.activebpel.rt.bpel.server.engine.AeEngineFactory.preInit(AeEngineFactory.java:183)
at org.activebpel.rt.bpel.server.engine.AeEngineLifecycleWrapper.init(AeEngineLifecycleWrapper.java:73)
at org.activebpel.rt.axis.bpel.web.AeProcessEngineServlet.init(AeProcessEngineServlet.java:133)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1091)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:925)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:3880)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4141)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:759)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:739)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:524)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:603)
at org.apache.catalina.startup.HostConfig.deployDescriptors(HostConfig.java:535)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:470)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1118)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:310)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1020)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:718)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1012)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:442)
at org.apache.catalina.core.StandardService.start(StandardService.java:450)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:680)
at org.apache.catalina.startup.Catalina.start(Catalina.java:536)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:275)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
Caused by: org.activebpel.rt.AeException: Error creating Storage Provider.
at org.activebpel.rt.bpel.server.engine.storage.AeStorageFactory.createStorageProviderFactory(AeStorageFactory.java:117)
at org.activebpel.rt.bpel.server.engine.storage.AeStorageFactory.setConfiguration(AeStorageFactory.java:77)
at org.activebpel.rt.bpel.server.engine.storage.AePersistentStoreFactory.init(AePersistentStoreFactory.java:75)
... 31 more
Caused by: java.lang.UnsupportedOperationException
at org.apache.tomcat.dbcp.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:116)
at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:554)
at org.activebpel.rt.bpel.server.engine.storage.sql.AeDataSource.getConnection(AeDataSource.java:323)
at org.activebpel.rt.bpel.server.engine.storage.sql.AeJNDIDataSource.getConnection(AeJNDIDataSource.java:116)
at org.activebpel.rt.bpel.server.engine.storage.sql.AeSQLObject.getConnection(AeSQLObject.java:48)
at org.activebpel.rt.bpel.server.engine.storage.sql.AeSQLDatabaseType.getDatabaseType(AeSQLDatabaseType.java:68)
at org.activebpel.rt.bpel.server.engine.storage.sql.AeSQLStorageProviderFactory.validateDatabaseType(AeSQLStorageProviderFactory.java:175)
at org.activebpel.rt.bpel.server.engine.storage.sql.AeSQLStorageProviderFactory.setConfiguration(AeSQLStorageProviderFactory.java:93)
at org.activebpel.rt.bpel.server.engine.storage.sql.AeSQLStorageProviderFactory.(AeSQLStorageProviderFactory.java:60)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at org.activebpel.rt.bpel.server.engine.storage.AeStorageFactory.createStorageProviderFactory(AeStorageFactory.java:108)
... 33 more

solution:
make sure that the database username is not specified in both tomcat context datasource definition and the activebpel engine configuration (aeEngineConfig.xml)