What unityengin dll version should I have?

Questions & Answers
1

I’m using visual studio to code my Unity3D project. Currently it is not accepting the following code:

 using UnityEngine.EventSystems;
 using UnityEngine.UI;

When I look at the property inspector for the UnityEngine.dll it says that the “Runtime Version” is: v2.0.50727

My Unity Editor version is 5.1.1f1 Personal.
All other versions of the editor have been removed.

  • Is the dll version wrong?
  • is it too old or too new?
  • what is the most recent version?
  • do I need to download something?
  • where do I get it?
2

I needed to include this dll: Path_To_Unity_Installation/Editor/Data/UnityExtensions/Unity/GUISystem/UnityEngine.UI.dll