title: IsTriggerEnter does not seem to be working in Unity
body: <p>In a 2D gameworld, I have a player square with a <code>Rigidbody 2D</code>, <code>Box Collider 2D</code>, a bigger <code>Box Collider 2D</code> as a trigger (which means the <code>IsTrigger</code> box is checked!), and a script handling <code>OnTriggerEnter</code>. And an enermy square with a <code>Rigidbody 2D</code> and <code>Box Collider 2D</code>.</p>
  
  <p>But when I move my player to the enermy, my <code>OnTriggerEnter</code> was never triggered (which means no debug log is shown). And I know the colliders worked because I can push the enemy around.</p>
  
  <p>Where did I set it wrong?</p>
  
  <pre><code>private void OnTriggerEnter(Collider other)
  {
      Debug.Log(other.gameObject.name);
  }
  </code></pre>
  
  <p><strong>Screenshots (I don't know if this is this is what <code>Kashif Siddiqui</code> wanted!?):</strong>
  <a href="https://i.stack.imgur.com/GFkk1.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GFkk1.jpg" alt="Screenshot 1"></a>
  <a href="https://i.stack.imgur.com/KSEHb.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KSEHb.jpg" alt="Screenshot 2"></a></p>