Dropdown component missing in Linux Unity ?

using UnityEngine;
using UnityEngine.UI;
using System.Collections.Generic;
using System.Collections;

public class MessageManager : MonoBehaviour {

	private static MessageManager mInstance;
	public Dropdown dropdown;

And it’s telling me that Dropdown could not be found I am using 5.1.3 For Linux ( Ubuntu ). Can anyone give me some info this seems really strange as I’ve made 2 games so far and no other problems like this have come up.

That’s because the dropdown control was introduced in 5.2… https://unity3d.com/unity/whats-new/unity-5.2