jQuery does not handle load event for iframe which are not yet added to the document as you can do with img.

Test case:

http://jsfiddle.net/5KK7w/

Works:

$('body').append('<iframe id="iframe1"/>');

$('#iframe1').load(function(){

alert('iframe loaded');

}).attr({'src':srcIframe});

Does not work:

$('<iframe id="iframe1"/>').load(function(){

alert('iframe loaded');

$(this).appendTo('body');

}).attr({'src':srcIframe});