Error in using Sensu handler "default"

Hi ,
I am a newbie in Sensu . Following are the configs and the error I am getting while running sensu-server.

The server does not gets the response of the command executed on the client.

/etc/sensu/conf.d/check_cpu_metrics.json

{

“checks”: {

“check_cpu” : {

“handlers”: [“default”],

“command”: “check-cpu.rb”,

“subscribers”: [“production”],

“interval”: 10

}

}

}

/etc/sensu/conf.d/handler_default.json

{

“handlers”: {

“default”: {

“type”: “set”,

“handlers”: [

“stdout”

]

},

“stdout”: {

“type”: “pipe”,

“command”: “cat”

}

},

}

**ERROR : **

**tail -f **/var/log/sensu/sensu-server.log

{“timestamp”:“2015-02-25T11:45:49.842797-0500”,“level”:“info”,“message”:“publishing check request”,“payload”:{“name”:“check_cpu”,“issued”:1424882749,“command”:“check-cpu.rb”},“subscribers”:[“production”]}

{“timestamp”:“2015-02-25T11:45:54.938239-0500”,“level”:“error”,“message”:“unknown handler”,“handler_name”:“default”}

{“timestamp”:“2015-02-25T11:45:57.838760-0500”,“level”:“info”,“message”:“determining stale clients”}

{“timestamp”:“2015-02-25T11:45:57.861205-0500”,“level”:“error”,“message”:“unknown handler”,“handler_name”:“default”}

{“timestamp”:“2015-02-25T11:45:57.866314-0500”,“level”:“error”,“message”:“unknown handler”,“handler_name”:“default”}

{“timestamp”:“2015-02-25T11:45:59.845355-0500”,“level”:“info”,“message”:“publishing check request”,“payload”:{“name”:“check_cpu”,“issued”:1424882759,“command”:“check-cpu.rb”},“subscribers”:[“production”]}

tail -f /var/log/sensu/sensu-client.log

{“timestamp”:“2015-02-25T11:45:12.657319-0500”,“level”:“warn”,“message”:“ignoring config file”,“file”:"/etc/sensu/conf.d/handler_default.json"}

{“timestamp”:“2015-02-25T11:45:12.657396-0500”,“level”:“warn”,“message”:“loading config file”,“file”:"/etc/sensu/conf.d/api.json"}

{“timestamp”:“2015-02-25T11:45:12.657502-0500”,“level”:“warn”,“message”:“config file applied changes”,“file”:"/{“timestamp”:“2015-02-25T11:45:12.657589-0500”,“level”:“warn”,“message”:“loading config file”,“file”:"/etc/sensu/conf.d/redis.json"}

{“timestamp”:“2015-02-25T11:45:12.657687-0500”,“level”:“warn”,“message”:“config file applied changes”,“file”:"/etc/sensu/conf.d/redis.json",“changes”:{“redis”:[null,{“host”:“localhost”,“port”:6379}]}}

{“timestamp”:“2015-02-25T11:45:12.657815-0500”,“level”:“warn”,“message”:“loading config file”,“file”:"/etc/sensu/conf.d/rabbitmq.json"}

{“timestamp”:“2015-02-25T11:45:12.657939-0500”,“level”:“warn”,“message”:“config file applied changes”,“file”:"/etc/sensu/conf.d/rabbitmq.json",“changes”:{“rabbitmq”:[null,{“ssl”:{“cert_chain_file”:"/etc/sensu/ssl/cert.pem",“private_key_file”:"/etc/sensu/ssl/key.pem"},“host”:“localhost”,“port”:5671,“vhost”:"/sensu",“user”:“sensu”,“password”:“REDACTED”}]}}

{“timestamp”:“2015-02-25T11:45:12.658024-0500”,“level”:“warn”,“message”:“loading config file”,“file”:"/etc/sensu/conf.d/check_cpu_metrics.json"}

{“timestamp”:“2015-02-25T11:45:12.658132-0500”,“level”:“warn”,“message”:“config file applied changes”,“file”:"/etc/sensu/conf.d/check_cpu_metrics.json",“changes”:{“checks”:{“check_cpu”:[null,{“handlers”:[“default”],“command”:“check-cpu.rb”,“subscribers”:[“production”],“interval”:10}]}}}

{“timestamp”:“2015-02-25T11:45:12.661380-0500”,“level”:“warn”,“message”:“loading extension files from directory”,“directory”:"/etc/sensu/extensions"}