how to change the Parent of an object to the current object that a script is on?

so im trying to instantiate a new object, set its parent to be the parent of the objewct that the current script is attached to, then set its rotation to the rotation of the parent object. i keep getting anull reference exception whenever i try to set the parent of the newly instantiated object. What am i doing wrong here?

		Vector3 selectLocation = new Vector3 (transform.position.x, transform.position.y - 2, transform.position.z);
		Vector3 orbitLocation = new Vector3 (transform.position.x + .3f, transform.position.y - 1, transform.position.z - 2f);

			temp_select = Instantiate(selectButton, selectLocation, selectButton.rotation)as GameObject; 
		temp_orbit = Instantiate (orbitButton, orbitLocation, orbitButton.rotation)as GameObject;

			temp_select.transform.parent = this.gameObject.transform;
			temp_orbit.transform.parent = this.gameObject.transform;

		temp_select.transform.rotation = selectButton.transform.parent.transform.rotation;
		temp_orbit.transform.rotation = orbitButton.transform.parent.transform.rotation;

	public void killButtons()
		Destroy (temp_select);
		Destroy (temp_orbit);

You need to use SetParent() instead of setting it directly.