Problem with AIM to SHOOT script

I’m having a problem with a script, I’m really new to to coding but I don’t see anything wrong with it. The script makes you have to hold down FIRE2 to press FIRE1 to shoot. Whenever I hold down FIRE2 and press FIRE1 it just won’t shoot. It works when I take out the line with having to use FIRE2.

If anyone knows what I’m doing wrong with this code, I need help. Thanks in advanced!

var projectile : Transform;

function Start() {

function Update() {
	if(Input.GetButtonDown("Fire2")) {
		if (Input.GetButtonDown("Fire1")) {
			var Clone : Transform;
			clone = Instantiate(projectile, transform.position, transform.rotation);
			clone.rigidbody.AddForce(clone.transform.forward * 1000);
			rigidbody.AddRelativeForce(Vector3.forward * Time.deltaTime * 1000);
			Physics.IgnoreCollision(clone.collider, collider); 

Input.GetButtonDown() only returns true for the frame in which it is pressed. Replace it with: