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[912-GUI+Javascript.png|912]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!!

You are not closing the brackets of your if statements…