title: System.IO.File' does not contain a definition for `AppendAllText' error in Unity3D?
body: <p>I am very new to Unity3d and tried to open an existing project. While playing it shows the following error. </p>
  
  <p>Assets/Scripts/DataAccess.cs(39,30): error CS0117: <code>System.IO.File' does not contain a definition for</code>AppendAllText'</p>
  
  <p>I dont have any idea about how to solve this. I get stuck over here.</p>
  
  <p>It would be appreciating if anyone solve this problem.</p>
  
  <p>Thanks in advance...</p>