Plz help me

I have 2 kafka and 1 zookeeper

But When I use kafka producer to send msg to zookeeper ,It just send msg to
broker 0,but not broker 1.

./kafka/bin/kafka-producer-perf-test.sh --brokerinfo zk.connect=
211.43.180.171:2181 --messages 100000 --topic my_topic --threads 2
--message-size 200 --async=true

*2013-07-16 15:59:55,158] INFO Creating async producer for broker id = 1 at
10.10.6.201:9092(kafka.producer.ProducerPool)
[2013-07-16 15:59:55,158] INFO Creating async producer for broker id = 0 at
10.10.7.166:9092(kafka.producer.ProducerPool)*
[2013-07-16 15:59:55,159] INFO Producer properties = {zk.connect=
211.43.180.171:2181, compression.codec=0, buffer.size=65536,
reconnect.interval=2147483647, batch.size=200, producer.type=async,
queue.enqueueTimeout.ms <http://queue.enqueuetimeout.ms/>=-1} (kafka.tools.
ProducerPerformance$AsyncProducerThread)
[2013-07-16 15:59:55,159] INFO Messages per thread = 50000 (kafka.tools.
ProducerPerformance$AsyncProducerThread)
[2013-07-16 15:59:55,159] INFO Initiating client connection, connectString=
211.43.180.171:2181sessionTimeout=6000 watcher=org.I0Itec.zkclient.
ZkClient [ at ] 17bc72c0 (org.apache.zookeeper.ZooKeeper)
[2013-07-16 15:59:55,160] INFO Starting ZkClient event thread.
(org.I0Itec.zkclient.ZkEventThread)
[2013-07-16 15:59:55,167] INFO Opening socket connection to server /
211.43.180.171:2181(org.apache.zookeeper.ClientCnxn)
*[2013-07-16 15:59:55,417] INFO Connected to 10.10.7.166:9092 for producing
(kafka.producer.SyncProducer)*
[2013-07-16 15:59:56,656] INFO thread 0: 5000 messages sent 3351.2064
nMsg/sec 2.1521 MBs/sec (kafka.tools.ProducerPerformance$
AsyncProducerThread)
[2013-07-16 15:59:57,323] INFO thread 0: 10000 messages sent 7440.4762
nMsg/sec 4.8249 MBs/sec (kafka.tools.ProducerPerformance$
AsyncProducerThread)
[2013-07-16 15:59:57,774] INFO thread 0: 15000 messages sent 11086.4745
nMsg/sec 7.1401 MBs/sec (kafka.tools.ProducerPerformance$
AsyncProducerThread)
[2013-07-16 15:59:57,970] INFO thread 0: 20000 messages sent 25510.2041
nMsg/sec 16.3751 MBs/sec (kafka.tools.ProducerPerformance$
AsyncProducerThread)
[2013-07-16 15:59:58,101] INFO thread 0: 25000 messages sent 38167.9389
nMsg/sec 24.7269 MBs/sec (kafka.tools.ProducerPerformance$
AsyncProducerThread)
[2013-07-16 15:59:58,250] INFO thread 0: 30000 messages sent 33557.0470
nMsg/sec 21.6650 MBs/sec (kafka.tools.ProducerPerformance$
AsyncProducerThread)
[2013-07-16 15:59:58,395] INFO thread 0: 35000 messages sent 34722.2222
nMsg/sec 22.4402 MBs/sec (kafka.tools.ProducerPerformance$
AsyncProducerThread)
[2013-07-16 15:59:58,530] INFO thread 0: 40000 messages sent 36764.7059
nMsg/sec 23.6089 MBs/sec (kafka.tools.ProducerPerformance$
AsyncProducerThread)
[2013-07-16 15:59:58,687] INFO thread 0: 45000 messages sent 31847.1338
nMsg/sec 20.4403 MBs/sec (kafka.tools.ProducerPerformance$
AsyncProducerThread)
[2013-07-16 15:59:58,797] INFO thread 0: 50000 messages sent 45454.5455
nMsg/sec 29.1881 MBs/sec (kafka.tools.ProducerPerformance$
AsyncProducerThread)
[2013-07-16 15:59:58,797] INFO Closing all async producers
(kafka.producer.ProducerPool)

producers always connect to broker 0,I don't know why

Plz help me.