javascript not loading in a dynamic iframe - php

Question

I've spent hours reading javascript books, patterns and looking on stackoverflow questions but I'm stuck on loading something dynamically into an iframe
Goal Click on a button, (1) ajax post to temp.php with data (ex. src, height, width, id).
(2) temp.php sets up the iframe and returns the respective html. (3) Javascript prepends the data.
Here is the respective code I have so far
(1)
$.ajax({
type:"POST",
data:{
'src':"target.php",
'frame_height':$(".mydiv").height(),
'frame_width':$(".mydiv").width()
},
url:"temp.php",
success:function (inHtml) {
loadConversation(inHtml,
I've loaded the POST variables into the respective php variables already.
(2)
<iframe id="myTestFrame" src="<?php echo $src; ?>" width="<?php echo $width; ?>"
height="<?php echo $height; ?>" frameborder="0">
<p>Your browser does not support iframes.</p>
(3)
$('.mydiv').prepend(inHtml);
Please assume that the syntax is done correctly.
the target.php does run a simple javascript code initializing a scroll plugin:
$(function () {
var Scroll = (function () {
var init = function () {
$("#content-1").mCustomScrollbar({});
$(".inner_content").mCustomScrollbar({autoDraggerLength:true});
$(".output a[rel~='_mCS_1_scrollTo']").click(function (e) {
e.preventDefault();
$("#content-1").mCustomScrollbar("scrollTo", $(this).attr("href"));
});
};
return { init:init };
})();
Scroll.init();
});
What's happening now is that I can call temp.php directly from the webserver and it will load properly.
expected
But once it's called from the main site - it breaks (and an 'undefined' to boot)
broken in main site
I've done the same iframe post and then update src dynamically with another php page with a plugin and it works fine (same on click, ajax post, prepend(html) , I'm completely lost). The main site is running it inside a tabbed interface from jquery UI, but I don't think that makes any difference - what I've found so far is that if I insert a simple 'alert(document.height)' into the init function, the alert box will contain 0, so I think the javascript runs before the iframe has finished loading - but Firebug shows that the Response HTML in NET is perfectly fine and the code is rather short. (The script is placed last right before the close brace)