Save/ Load game script in main menu

I want to create a saving and loading script so that my users can enjoy and can pause the game for a while. But I have a problem coming up in my script:

     var OptionUI = false;
 enum Mode {Easy =2}
 
 function Update () 
 {
 
 }
 
 function OnGUI()
 {
     GUI.Box(Rect(Screen.width /2 - 60,Screen.height /2 - 179,120,340, "Main Menu"));
     
     if(OptionUI == false)
     {
         if(GUI.Button(Rect(Screen.width /2 - 50,Screen.height /2 - 120,109,39, "Play Game"))
         {
              Application.LoadLevel(1);
         }
         if(GUI.Button(Rect(Screen.width /2 - 50,Screen.height /2 - 90,109,39, "Options"))
         {
              OptionUI = true;
         }
         if(GUI.Button(Rect(Screen.width /2 - 50,Screen.height /2 - 60,109,39, "Exit"))
         {
              Application.Quit();
         }    
     }
     
     if(OptionUI = true)
     {
         if(GUI.Button(Rect(Screen.width /2 - 50,Screen.height /2 - 50,109,39,"Easy"))
         {
              
         } 
         
         if(GUI.Button(Rect(Screen.width /2 - 50,Screen.height /2 - 50,109,39,"Medium"))
         {
              
         }
         
         if(GUI.Button(Rect(Screen.width /2 - 50,Screen.height /2 - 50,109,39,"Hard"))
         {
              
         }                        
     }
 }
 125![alt text][1]125

Error is: Assets/GUI.js(16,9): BCE0044: expecting ), found '{'.

(Filename: Assets/GUI.js Line: 16)

Assets/GUI.js(20,9): BCE0044: expecting ), found '{'.

(Filename: Assets/GUI.js Line: 20)

Assets/GUI.js(24,9): BCE0044: expecting ), found '{'.

(Filename: Assets/GUI.js Line: 24)

Assets/GUI.js(26,9): BCE0044: expecting EOF, found '}'.

(Filename: Assets/GUI.js Line: 26) Thank you in advance if you can help me!!! I beg you!!!Help me!!

[1]: http://unity3d.qatohost.com/storage/temp/912-GUI+Javascript.png