Usage Manager memory limit (104857600) reached for a topic

Hi,

I got following message:

INFO | jvm 1 | 2014/05/13 07:02:39 | INFO | TopicSubscription:
consumer=ID:JSANDS-PC3-53028-1399897473907-0:0:1:1, destinations=1,
dispatched=32766, delivered=0, matched=30386, discarded=0: Pending message
cursor
[org.apache.activemq.broker.region.cursors.VMPendingMessageCursor [ at ] e00788] is
full, temp usage (0%) or memory usage (100%) limit reached, blocking message
add() pending the release of resources.
INFO | jvm 1 | 2014/05/13 07:02:39 | INFO | Usage Manager memory limit
(104857600) reached for topic://BROADCAST_MESSAGING_TOPICFTPCAPP01.
Producers will be throttled to the rate at which messages are removed from
this destination to prevent flooding it. See
http://activemq.apache.org/producer-flow-control.html for more info
INFO | jvm 1 | 2014/05/13 07:02:40 | INFO | Usage Manager memory limit
reached. Stopping producer (ID:FTPCSOS01-51636-1399733296121-0:0:1:1) to
prevent flooding topic://BROADCAST_MESSAGING_TOPICFTPCAPP01. See
http://activemq.apache.org/producer-flow-control.html for more info
(blocking for: 1s)
INFO | jvm 1 | 2014/05/13 07:02:41 | INFO | Usage Manager memory limit
reached. Stopping producer (ID:PTS10-60482-1399733597139-0:0:1:1) to prevent
flooding topic://BROADCAST_MESSAGING_TOPICFTPCAPP01. See
http://activemq.apache.org/producer-flow-control.html for more info
(blocking for: 1s)

Following are my configuration:

<destinationPolicy>
<policyMap>
<policyEntries>
<policyEntry topic=">" producerFlowControl="true"
memoryLimit="1mb">
<pendingSubscriberPolicy>
<vmCursor />
</pendingSubscriberPolicy>
</policyEntry>
<policyEntry queue=">" producerFlowControl="true"
memoryLimit="1mb">

</policyEntry>
</policyEntries>
</policyMap>
</destinationPolicy>

Someone can help me to explain why it happens?

Thanks.