Bulk load gets Validation Failed error

Why do I get
{"error":"ActionRequestValidationException[Validation Failed: 1: no
requests added]","status":500}

with this (tweet) data:

{ "index" : { "_index" : "twitter", "_type" : "tweet", "_id" : "510"}}
{"contributors":null,"text":"@LaurenFritsky do you have a #blog or a
magazine where you write? Would like to see
it","geo":null,"retweeted":false,"in_reply_to_screen_name":"LaurenFritsky","truncated":false,"entities":
{"urls":[],"hashtags":[{"text":"blog","indices":
[29,34]}],"user_mentions":[{"id":42732359,"name":"Lauren","indices":
[0,14],"screen_name":"LaurenFritsky","id_str":"42732359"}]},"in_reply_to_status_id_str":"91044279744610304","id":
91053923250601984,"in_reply_to_user_id_str":"42732359","source":"TweetDeck</
a>","favorited":false,"in_reply_to_status_id":
91044279744610304,"retweet_count":0,"in_reply_to_user_id":
42732359,"created_at":"Wed Jul 13 07:58:41 +0000
2011","id_str":"91053923250601984","place":null,"user":
{"location":"India","default_profile":false,"statuses_count":
142,"profile_background_tile":true,"lang":"en","profile_link_color":"0084B4","id":
266647712,"following":null,"protected":false,"favourites_count":
0,"profile_text_color":"333333","contributors_enabled":false,"description":"Wildlifer,
photographer, explorer, cyclist, looking for the next adrenalin rush.
Part of GoMissing Expeditions @ http://www.gomissingexpeditions.com","verified":false,"name":"Saurabh
Kapur","profile_sidebar_border_color":"C0DEED","profile_background_color":"C0DEED","created_at":"Tue
Mar 15 15:31:33 +0000
2011","default_profile_image":false,"followers_count":
21,"geo_enabled":false,"profile_image_url_https":"https://
si0.twimg.com/profile_images/1273821154/gomissing-guy-
twitter_normal.jpg","profile_background_image_url":"http://
a2.twimg.com/profile_background_images/217952151/twitter-bg-
gomissingguy.jpg","profile_background_image_url_https":"https://
si0.twimg.com/profile_background_images/217952151/twitter-bg-
gomissingguy.jpg","follow_request_sent":null,"url":"http://
www.gomissing.com","utc_offset":null,"time_zone":null,"notifications":null,"friends_count":20,"profile_use_background_image":true,"profile_sidebar_fill_color":"DDEEF6","screen_name":"GoMissingGuy","id_str":"266647712","show_all_inline_media":false,"profile_image_url":"http://a1.twimg.com/profile_images/1273821154/gomissing-guy-twitter_normal.jpg","is_translator":false,"listed_count":1},"coordinates":null}

What is wrong?