ActionScript 3.0 :: Using Mc Class In Hit Test?

In my platform game my character shoots bullets from a gun,these bullets are loaded from a 'bullet' class. A new instance of this class has the variable name 'bulletVar'. I can adjust the bullets x and y position like so:

bulletVar.x = 253;

But I also want to use it in a hitTestObject, I thought that the following code would work, but it does not!

stage.addEventListener(Event.ENTER_FRAME, hitEnemy);
function hitEnemy(event:Event):void
{
if (bulletVar.hitTestObject(enemy_mc))

[code]....

Here's my code to call a bullet:

var bulletVar:bullet = new bullet();
this.addChild(bulletVar);