$(document).ready(function(){
var options = {
target : "#responseTarget",
iframeTarget : "#responseTarget",
beforeSubmit: function(){
$("<iframe name='iframeUploader' onload='init_iframe(window.iframeUploader);' />")
.prependTo("#upload_preview")
.attr({"id": "responseTarget"})
.css({"border":"none","padding":"none","width":"150","height":"100"});
},
success: function(data) {alert("ASDASD");}, // Problem is in here...
error: function(r){alert("An error..." + r);}
};

$("#upload_form").ajaxForm(options);
});