cant read the json fom yahoo pipe

$(function(){
            $.getJSON('http://pipes.yahoo.com/pipes/pipe.run?_id=7ba696f34ae17b6fa8f5d4开发者_StackOverflowde13064dea&_render=json&callback=?',function(data){alert('called')});

            });

i am using the above code to acess the a yahoo pipe i created to convert the last.fm xml output to json.but the firebug console output is showing me

invalid label
http://pipes.yahoo.com/pipes/pipe.run?_id=7ba696f34ae17b6fa8f5d4de13064dea&_render=json&callback=jsonp1276401573015
Line 1

while i can view the result using a browser in a perfectly normal way.also i validated the json using jsonlint and it shows the json is valid,what migt be the problem ?

It's _callback not callback according to http://discuss.pipes.yahoo.com/Message_Boards_for_Pipes/threadview?m=mm&bn=pip-DeveloperHelp&tid=2097&mid=2098&tof=3&o=rr&rt=2&frt=2&off=1