[AS3] erase Loaders if they exist ?

Hello (excuse my bad english / I'm an ol french)

I load a lot of ".swf" during the main, like this :

var conteneurImage2:Loader = new Loader();

var image2:URLRequest = new URLRequest("test/intro.swf");

conteneurImage2.load(image2);

this.addChild(conteneurImage2);

I want to erase the loaders, like this

conteneurImage2.unloadAndStop();

removeChild(conteneurImage2);conteneurImage2 = null;

conteneurImage2.visible = false;

But sometimes, some loaders don't exist. I know I need to use the function "if", but I don't succeed. I try this

if (conteneurImage2)

{conteneurImage2.unloadAndStop();

removeChild(conteneurImage2);conteneurImage2 = null;

conteneurImage2.visible = false;}

or this :

if (conteneurImage2 != null;)

{conteneurImage2.unloadAndStop();

removeChild(conteneurImage2);conteneurImage2 = null;

conteneurImage2.visible = false;}

It doesn't work. The loader is not deleted.

I thank you very much.