Restricted resource set on EJB? No DB connection...

I get the following error:

Caused by: com.sap.engine.services.dbpool.exceptions.BaseSQLException: ResourceException occurred in method ConnectionFactoryImpl.getConnection(): com.sap.engine.services.connector.exceptions.BaseResourceException: Cannot get connection. Reason: the thread of component "ejbContexts/.../TreeHolderBean" in application "..." is currently associated with a restricted resource set and it is not allowed to get connection within it.

I get this from a Web Dynpro application, that references an EJB application through local interface, the EJB wants to connect to Database through a stateful session bean.

No idea what that means... Any help?

Thx,

Frank