Poller loosing messages

[nit_mis]

Environment: Using spring integration 1.4, Spring (2.5.6), JDK 1.5.
Problem: Loosing some messages in polling
Flow: Order booked, paid. However poller seems to be loosing some orders when booked and paid concurrently. So if booking nearly 1000 orders, at the same time start paying for it.
Could someone please point out what wrong I am doing?
Note: The config works perfectly with small number of orders (say 10).

<beans>
	<bean id="transactionManager" class="org.springframework.jms.connection.JmsTransactionManager">
    	   <property name="connectionFactory" ref="jmsConnectionFactory" />
  	</bean>
  	
  	<tx:annotation-driven transaction-manager="transactionManager"/>
  	
	<integration:poller id="inPoller" default="true">
		<integration:interval-trigger interval="60" fixed-rate="true"
			time-unit="SECONDS" />
		<integration:transactional transaction-manager="transactionManager" propagation="REQUIRED" />
	</integration:poller>
	
	<int-jms:inbound-channel-adapter id="jmsReportInBooked" connection-factory="jmsConnectionFactory" 
			destination-resolver="jndiDestinationResolver" destination-name="reportEventQueue" 
		channel="eventChannel"/>
	
	<integration:channel id="eventChannel"/>
	
	<integration:header-value-router input-channel="eventChannel" header-name="EVENT_TYPE">
		<integration:mapping value="BOOKED" channel="bookedEventChannel"/>
		<integration:mapping value="PAID" channel="paidEventChannel"/>
	</integration:header-value-router>
	
	<integration:channel id="bookedEventChannel"/>
	
       <integration:service-activator input-channel="bookedEventChannel" ref="bookedEventMessageHandler" 
		method="onMessage"/>
		
	<integration:channel id="paidEventChannel"/>
	
	<integration:service-activator input-channel="paidEventChannel" ref="paidEventMessageHandler" 
		method="onMessage"/>
		
	
</beans>