Menu Button help

I’m trying to add function to these Menu buttons. The Menu button shows all the buttons, and the Close one hides them again. I want the Credits button to pop up a new box when it’s clicked.

#pragma strict

var showMoreGui = false;
var showCredits = false;
function OnGUI () {
    if (GUI.Button (Rect (650,300,100,20), "Open Menu"))
        showMoreGui = true;
    if (showMoreGui)  {
        (GUI.Button (Rect (650,350,100,20), "Play"));
        (GUI.Button (Rect (650,400,100,20), "Options"));

// this is the code that doesn’t work, the credits button shows, but does nothing on clicking.

      {  if(GUI.Button (Rect (650,450,100,20), "Credits")){
          showCredits = true;
         if(showCredits) {
         (GUI.Box (Rect (600,300,100,100), "Credits Box"));}
   if (GUI.Button (Rect (650,500,100,20), "Close"))
            showMoreGui = false;

You need to take

if(showCredits) {
    (GUI.Box (Rect (600,300,100,100), "Credits Box"));}

out of

if(GUI.Button (Rect (650,450,100,20), "Credits")){


else this part of the script is only executed once, when you click on the button.