Connection Pool JDBC 3.5

Hi all, IDS 11.5, JDBC 3.50 I tried to use connection pooling, without any JNDI-Registrations. IfxConnectionPoolDataSource cpds = new IfxConnectionPoolDataSource(); cpds.setIfxIFXHOST(m_hostname); cpds.setPortNumber(m_port); cpds.setServerName(m_dbservername); cpds.setUser(m_username); cpds.setPassword(m_password); cpds.setDatabaseName(m_databasename); cpds.setIfxCPMInitPoolSize(500); cpds.setIfxCPMMaxConnections(101); cpds.setIfxCPMMinPoolSize(50); cpds.setIfxCPMMaxPoolSize(100); cpds.setIfxCPMAgeLimit(-1); cpds.setIfxCPMMinAgeLimit(-1); cpds.setIfxCPMServiceInterval(0); All that seems to be OK, because cpds.getPooledConnection().getConnection() returns a IfxSqliConnReUsableConnection-Object, which works perfect. But when I close this connection, by "connection.close()", or "((IfxSqliConnReUsableConnection)connection).scrubConnection()", the connection-pool does not free that connection so that it can be reused. Creating and closing more and more connections, results in exceeding the maximal number of allowed connections. Any Ideas? Thanks for any hint! Greetings Markus