Dynamic MC depth swap

Question

i have several duplicated movie clips, and want to have 2
buttons that swap the depth of these so that the user can page
through (like pages of a book).
the first part of the code generates the movie clips and puts
them on different depths (this all works fine):
function GeneratePortfolio(portfolio_xml) {
var portfolioPictures = portfolio_xml.firstChild.childNodes;
// thumb vars (unrelated)
var x_pos = 0;
var y_pos = 0;
var col_count = 0; // columns
var col_count_max = 4; // max number of columns per row
var row_count = 0; // rows
var row_count_max = 6; // max number of rows per row
// calculate required number of menu pages
var menu_max = Math.ceil((portfolioPictures.length) /
(col_count_max * row_count_max)) - 1; // number of menu pages
required
trace ("menu_max = " + menu_max);
// generate menu pages
if (menu_max > 1) {
for (var m = 2; m <= menu_max; m++) {
_root.attachMovie("menu_mc", "menu_mc"+m,
this.getNextHighestDepth());
thisMenu = _root["menu_mc"+m];
thisMenu.text1 = m;
thisMenu._x = 14;
thisMenu._y = 41;
// move first page to top
menu_mc1.swapDepths(thisMenu);
pagation_nav.swapDepths(menu_mc1);
_root.m_page = 1;
_root.m_page_swap = m_page;
this next part is where i have the problem. this function
gets activated when the "next" button is pressed. the traces for
both "m_page" and "m_page_swap" register good. but "m_page_swap"
comes up undefined when applied to the end of "m_menu", even though
this works with "m_page". so, untimately, the swapDepths method
does not work.
can anyone help me?!
pagation_nav.b_nextPage.onRelease = function() {
m_page_swap = m_page + 1;
trace ("m_page = " + m_page);
trace ("m_page_swap = " + m_page_swap);
trace ("swap1 " + (_root["menu_mc"+m_page]));
trace ("swap2 " + (_root["menu_mc"+m_page_swap]));
_root["menu_mc"+m_page].swapDepths(_root["menu_mc"+m_page_swap]);
_root.m_page++;
~ M

Answer 1

More research into depth swapping and removal of MCs revealed
an inability to repeatedly set the depth of a dynamically created
MC. The code is called every 2 secs (for dev for now) via a
setInterval(). One would expect the value of n to increase and it
does, but that value does not get 'piped through' to the argument
of the createEmptyMovieClip() method.
The code below returns this output:
first mc : 5
n:5
first mc : 5
n:6
first mc : 5
n:7
Any thoughts on why this happens, and ways around it, would
be deeply appreciated. This is a huge stumbling block and my
program was built on the assumption I could do something like this
cheers
mm66