AddForce not working on Rigidbody2D.

I have a floating island that Translates up and down with a Rigidbody2D (Gravity Scale = 0). I’m trying to AddForce it upwards when the Player lands on it but it just floats down with the character. I’ve tried disabling the ‘floating’ but AddForce still won’t kick in. Debug.Log shows Player entering the collider.

bool goUp = false;

	void Update ()
	{
		if (goUp == true)
			driftUp ();
		else if (goUp == false)
			driftDown ();
	}

	void driftUp ()
	{
		transform.Translate (Vector2.up * .05f * Time.deltaTime);

		if (transform.position.y > -.9f)
			goUp = false;
	}

	void driftDown ()
	{
		transform.Translate (-Vector2.up * .05f * Time.deltaTime);

		if (transform.position.y < -2)
			goUp = true;
	}

	void OnCollisionEnter2D (Collision2D contact)
	{
		if (contact.gameObject.tag == "Player")
			rigidbody2D.AddForce (Vector2.up * 100f * Time.deltaTime);
	}

Remove Time.deltaTime.