when have outputs for zeromq and kafka, only zeromq can work?

I've set up 1 input config (zeromq) and 2 output configs (kafka and elasticsearch) for logstash in one of my server.
Learning from https://www.elastic.co/guide/en/logstash/current/advanced-pipeline.html#testing-second-pipeline, I think same logs can output to both kafka and elasticsearch.

But the result shows most of logs are output to only elasticsearch, and no log output to kafka in the very beginning when logstash service started. No error in logstash log, and I'm so confused why?
- Version: logstash 2.3.2
- Operating System: Ubuntu 14.04
- Config File (if you have sensitive info, please remove it):
I have 1 input config file and 2 output config files as below:

`input_zeromq`:
input {
zeromq {
topology => 'pushpull'
type => 'pull-input'
}
}

`output_kafka`:
output {
kafka {
topic_id => 'logstash_logs'
bootstrap_servers => 'aaaa:9092'
}
}

`output_elasticsearch`:
output {
elasticsearch {
hosts => ['bbbb:9200']
}
}