Some of the collisions are not responding - actionscript-3

Question

im developing a game; its like a space craft going horizontally and enemy crafts coming oppositely..Enemies are destroyed only when it collides with the trail of the craft.
Here is the main class:
public function Velocity() {
//int static var
trailspeed = 10;
shipspeed = 5;
//init ship//
ship = new Ship();
ship.x = 337;
ship.y = 216;
//int arrays
enemies = new Array();
//init starting state
score = 0;
health = 100;
//Events
addEventListener(Event.ENTER_FRAME, motion);
stage.addEventListener(KeyboardEvent.KEY_DOWN, keydown);
stage.addEventListener(KeyboardEvent.KEY_UP, keyup);
//init container and trail
_cont = new MovieClip();
//addChild
addChild(_cont);
addChild(ship);
timerset();
}
public function motion(e:Event){
//adding the trails
trail = new Trail();
trail.x = ship.x;
trail.y = ship.y;
_cont.addChild(trail);
checkcollision();
}
public function checkcollision(){
for(var _e:int = enemies.length - 1; _e >=0; _e--){
for(var _t:int = _cont.numChildren - 1; _t >=0; _t--){
if(enemies[_e].hitTestObject(_cont.getChildAt(_t))){
enemies[_e].remove();
return;
}
}
}
}
public function removeenemies(_e:Enemy){
for(var i in enemies){
if(enemies[i] == _e){
enemies.splice(_e);
}
}
}
and here is the Enemy class:
public class Enemy extends MovieClip {
private var _speed:Number;
public function Enemy(ypos, speed) {
this.x = 550;
this.y = ypos;
_speed = speed;
addEventListener(Event.ENTER_FRAME, motion);
}
public function motion(e:Event){
this.x -= _speed;
checkoffscreen();
}
public function remove(){
MovieClip(parent).removeenemies(this);
MovieClip(parent).removeChild(this);
removeEventListener(Event.ENTER_FRAME, motion);
return;
}
public function checkoffscreen(){
if(this.x < 0){
MovieClip(parent).removeenemies(this);
MovieClip(parent).removeChild(this);
removeEventListener(Event.ENTER_FRAME, motion);
}
}
}
}
The problem here is after 2 or 3 successful collision detections one goes undetected.. and hence the chances is like 2/3 ...how can i program a 100% successful collision???pls help

Answer 1

I want to recommend not to delete objects from within themselves, instead have a simple isDead boolean inside the the Enemy and in the main class when you loop through enemies check if isDead is set to true, if so then remove the object from the array and delete it from the Stage; no need for removeenemies().
Back to the real problem you're having. You're doing a good job iterating through the list of enemies in reverse since you do expect to remove some objects, that of course results in shift of entries in the array.
It's hard to say what's wrong with this code. I'd say lose removeenemies(). Move any collision testing inside the Enemy and in the Main keep everything in a nice linear update function like so:
public function update() {
for(var i:int = enemies.length - 1; i >=0; i--){
var enemy:Enemy = enemies[i];
enemy.checkCollision(); // Can set isDead = true;
if(enemy.isDead) {
enemies.splice(i);
removeChild(enemy);
}
}
}

Answer 2

Finally I found out the answer.
the problem was with the removeenemies function
replacing splice(_e) wtih splice(_e, 1) solved the problem