HibernateTransactionManager rollback won't work

[callisto]

I'm facing a serious problem when dealing with the HibernateTransactionManager rollback method.
(I have to reimplement a jdbc layer with hibernate, while the api of the layer has to remain the same. Therefore I have to substitute a method wich uses the jdbc connection rollback method under the hood with a method that now uses the HibernateTransactionManager rollback method.)
I use the transactionManager the following way:

DefaultTransactionDefinition def = new DefaultTransactionDefinition();
def.setPropagationBehavior(TransactionDefinition.PROPAGATION_REQUIRED);
TransactionStatus status = transactionManager.getTransaction(def);
transactionManager.rollback(status);

I know that my transactionManager is configured properly and rollback works. This is because i implemented some tests with AbstractTransactionalDataSourceSpringContextTests. After every test everything is rolled back properly. Also calling

this.transactionManager.rollback(this.transactionStatus);

in a Testcase works fine.

But when doing it in another bean (with properly injected transactionManager) a rollback won't work. I've played with several PropagationBehaviors and combinations on where in the code I set them.

I also took the AbstractTransactionalDataSourceSpringContextTests source code and designed my class like this (especially the behavior of TransactionDefinition and TransactionStatus).

When debugging the code I discovered that "my variant" behaves very similiar to the one of the AbstractTransactionalDataSourceSpringContextTests class.
In the Method "private void processRollback(DefaultTransactionStatus status)" of AbstractPlatformTransactionManager my variant does either a "doRollback(status);" or a"doSetRollbackOnly(status);" while the AbstractTransactionalDataSourceSpringContextTests rollback always does "doRollback(status);". This propagates forword to a "jdbcContext.connection().rollback();" and so on...

So to me, everything looks fine, but the results aren't...

Can anybody help with some hints on this?

Thanks in advance

ps: I have to stick to this pattern, so declarative or programmatic transaction demarcation is out of the way.

pps: i also tried the simple

Connection conn = DataSourceUtils.getConnection(dataSource);
conn.rollback();

or the more sophisticated?

TransactionAwareDataSourceProxy proxy = new TransactionAwareDataSourceProxy(dataSource); 
proxy.getConnection().rollback();

approach... but they won't work. The only rollback that worked so far was with AbstractTransactionalDataSourceSpringContextTests (same datasource, same transactionManager).

ppps:
spring 2.0.6
hibernate 3.2.4.sp1
hsql database (i also tried db2, but same result)