Beginner with flash help with calculator

Hi im new to flash and am a bit stuck on why my calculator dosnt work properly.

What happens is that when i just have the + coding it works fine.

Thats the same for the - code.

When I put the two together then it only allows on of them either + or - to work and not both.

What i need is both to work and to add code to make * and / work.

Thanks

Any and all help is appreciated!

Here is the code

//Code for + calculation
add_btn.onRelease = function ()
{
var number1:Number = Number(input1_txt.text);
var number2:Number = Number(input2_txt.text);
result_txt.text = Number1 + Number2
}

var value1:Number;
var value2:Number;
var answer:Number;
//Values will be + unless letters are entered then message appears
add_btn.onRelease = function(){
readInputs();
if ( validateInput() ){
performOperation( “add” );
displayResult();
} else {
result_txt.text = “You must enter numbers”
}

}

function readInputs() {
value1 = Number(input1_txt.text);
value2 = Number(input2_txt.text);
}
function validateInput(){

if ( isNaN(value1) || isNaN(value2) ){
return false;
} else {
return true;
}
}

function performOperation( op:String ){
if ( op == “add”) {
answer = value1 + value2;
}
}

function displayResult() {
result_txt.text = answer;
}
//code for - calculation
subtract_btn.onRelease = function ()
{
var number1:Number = Number(input1_txt.text);
var number2:Number = Number(input2_txt.text);
result_txt.text = Number1 - Number2
}

var value1:Number;
var value2:Number;
var answer:Number;

subtract_btn.onRelease = function(){
readInputs();
if ( validateInput() ){
performOperation( “subtract” );
displayResult();
} else {
result_txt.text = “You must enter numbers”
}

}

function readInputs() {
value1 = Number(input1_txt.text);
value2 = Number(input2_txt.text);
}
function validateInput(){

if ( isNaN(value1) || isNaN(value2) ){
return false;
} else {
return true;
}
}

function performOperation( op:String ){
if ( op == “subtract”) {
answer = value1 - value2;
}
}
//displays answer
function displayResult() {
result_txt.text = answer;
}