Twitter Search Trouble -

hi guys i'm trying use http://search.twitter.com/search.json pull feeds of users. seems work can't seem pull justinbieber's twitter feed keep getting empty results

i can pull wilw no prob

http://twitter.com/#!/wilw http://search.twitter.com/search.json?q=from:wilw  {"results":[{"from_user_id_str":"20300","profile_image_url":"http://a0.twimg.com/profile_images/421184034/qc_avatar_flip_normal.png","created_at":"wed, 11 may 2011 03:23:19 +0000","from_user":"wilw","id_str":"68154189968191488","metadata":{"result_type":"recent"},"to_user_id":null,"text":"that joke isn't funny anymore #valleysmiths (thank indulgence, , apologies. here endeth flood.)","id":68154189968191488,"from_user_id":20300,"geo":null,"iso_language_code":"en","to_user_id_str":null,"source":"<a href="http://twitter.com/">web</a>"}],"max_id":68154189968191488,"since_id":0,"refresh_url":"?since_id=68154189968191488&q=from%3awilw","next_page":"?page=2&max_id=68154189968191488&rpp=1&q=from%3awilw","results_per_page":1,"page":1,"completed_in":0.017642,"since_id_str":"0","max_id_str":"68154189968191488","query":"from%3awilw"} 

but when comes justinbieber (its work sorry)

http://twitter.com/#!/justinbieber http://search.twitter.com/search.json?q=from:justinbieber 

i [] results

{"results":[],"max_id":68133219333189632,"since_id":0,"refresh_url":"?since_id=68133219333189632&q=from%3ajustinbieber","results_per_page":1,"page":1,"completed_in":0.222307,"since_id_str":"0","max_id_str":"68133219333189632","query":"from%3ajustinbieber"} 

if getting tweets specific users should use get statues/user_timeline method instead of search api.

https://api.twitter.com/1/statuses/user_timeline.json?screen_name=justinbieber