C# NullReferenceException Error

I cannot figure out what is wrong with this but Unity keeps giving me a NullReferenceException: Object reference not set to an instance of an object for this on two lines of this.

this is the method where the errors occur;

void WeaponControl (Transform currentGun, string gunName, int gunDamage) {
		Transform otherMuzzleFlash;
		Transform otherBloodHole;
		Transform otherGunHole;
		if(Input.GetButtonDown("Fire1")&&!currentGun.animation.isPlaying) {
			otherMuzzleFlash = Instantiate(muzzleFlash, muzzle.position, Quaternion.identity) as Transform;
			otherMuzzleFlash.transform.parent = transform;
			currentGun.animation.Play(gunName + "Recoil");
			RaycastHit hit;
			if(Physics.Raycast(muzzle.transform.position, muzzle.transform.forward, out hit)) {
				Debug.DrawLine(transform.position, hit.point);
				if(hit.transform.tag != "Enemy") {
					otherGunHole = Instantiate(gunHole, hit.point + (hit.normal * 0.001f), Quaternion.LookRotation(hit.normal)) as Transform;
					otherGunHole.parent = hit.transform; //Error here
				} else {
					otherBloodHole = Instantiate(bloodHole, hit.point + (hit.normal * 0.001f), Quaternion.LookRotation(hit.normal)) as Transform;
					otherBloodHole.parent = hit.transform; //Error here
					hit.transform.SendMessage("ApplyDamage", gunDamage * damageMultiplier, SendMessageOptions.DontRequireReceiver);
					carnage += 1;

Changing otherGunHole and otherBloodHole into GameObjects instead of Transform seems to have worked. Thanks for your help.