Help with loaders pls pls pls

Hi im new here, the thing is im a noob in Flash too lol so i saw a tutorial on how to use loaders to load external jpg, that i can do but well i tried to modify the cose to put a next button and a back button so here is my code:

var n:Number = 0;
var i:Number = n+1;
var k:Number = n+2;
var j:Number = n+3;

comp1_btn.contentPath = “thumb”+i+".jpg";
comp2_btn.contentPath = “thumb”+k+".jpg";
comp3_btn.contentPath = “thumb”+j+".jpg";

function portfolioLoader (image) {
main_mc.contentPath = image;
}

comp1_btn.onRelease = function (){
portfolioLoader(“image”+i+".jpg");
}
comp2_btn.onRelease = function (){
portfolioLoader(“image”+j+".jpg");
}
comp3_btn.onRelease = function (){
portfolioLoader(“image”+k+".jpg");
}

btnNext.onRelease =function() {
n = n+3;
};

btnBack.onRelease =function() {
if (n>=4) {
i = i - 3;
j = j - 3;
k = k - 3;
};
if (n <= 3) {
i = 1;
j = 2;
k = 3;
};

};

stop();

[SIZE=5]The Problem:[SIZE=2]When i click on the Buttons the value of the variables changes only and just only inside the Button, but i wont change the value of the initial variables so can someone please help me fix this please :P, My MSN messenger is ([email protected]) email ([email protected]) please i would really apreciate if u guys help me with this[/SIZE][/SIZE]