riemann events not graphing

gistfile1.json

{
"host":"c-3d",
"service":"disk-md0/disk_ops/read",
"state":null,
"description":null,
"metric":18.99922062347532,
"tags":[
"collectd",
"i2.4xlarge"
],
"time":"2014-02-17T22:22:40.000Z",
"ttl":4.0,
"ds_index":"0",
"ds_name":"read",
"ds_type":"derive:rate",
"type":"disk_ops",
"plugin_instance":"md0",
"plugin":"disk"
}

{
"host":"c-3d",
"service":"disk-md0/disk_ops/read",
"state":null,
"description":null,
"metric":31.50093481111044,
"tags":[
"collectd",
"i2.4xlarge"
],
"time":"2014-02-17T22:22:42.000Z",
"ttl":4.0,
"ds_index":"0",
"ds_name":"read",
"ds_type":"derive:rate",
"type":"disk_ops",
"plugin_instance":"md0",
"plugin":"disk"
}