FLASH/PHP TextHighlighter

@ the following TextHighlighter
This code does not result in the source text box being searched for the specified string returned from the criteria text field. This should return to the result text field formated bold. Any knowledgeble help is requested.

<?php

	//PERFORM SEARCH AND REPLACE
	$result = str_replace($criteria, "<b>$criteria</b>", $source);
	//OUPUT RESULT TO FLASH
print "&result=" . urlencode($result);
?>	
//CREATING THE VARIABLES TO SEND AND RECEIVE DATA
lvOut = new LoadVars();
lvIn = new LoadVars();

//
lvIn.onLoad = function(success) {
	if (success) {
		//PHP VARIABLE TO TEXT BOX
		result.text = lvIn.result;
	} else {
		result.text = "Fail";
	}
};
//BUTTON ACTIONS
go_btn.onRelease = function() {
	lvOut.criteria = criteria.text;
	lvOut.sendAndLoad("highlight.php", lvIn, "POST");
};

I get interesting result when var source is also sent as an


lvOut.source = source.text;

FLA text boxes:
source(Input text)
criteria(Input text)
result(Dynamic text)