Scrollview not showing scroll bar and not scrolling

I am having a problem with the Scrollview. i am not getting the scroll bar to show up and it is not scroll.

public Vector2 scrollPostion = Vector2.zero;

...

void OnGUI()
    	{
    		if (listdownloaded) 
    		{
    			StopCoroutine("getlevels");
    			GUI.Window(1, new Rect(Screen.width*0.1f,Screen.height*0.1f, Screen.width*0.8f, Screen.height*0.8f), customlevelbuttonlist, "Custom Levels");
    		}
    		else if(...
    	}

	void customlevelbuttonlist(int windowID)
	{
		float count=0;
		scrollPostion=GUI.BeginScrollView(new Rect(Screen.width*0.05f, Screen.height*0.05f, Screen.width*0.75f, Screen.height*0.7f), scrollPostion, new Rect(0,0, Screen.width*0.7f, Screen.height*0.65f));
		foreach(CustomLevel level in CustomLevels)
		{
			if(GUI.Button(new Rect(0, buttonheight*count, Screen.width*0.7f, 45), level.Name))
			{
				Commons.levelLocation=CustomLevels[(int)count].location;
				updatepercent();
				UpDateAchievements();
				Application.LoadLevel(gotoSceneIndex);
				Debug.Log(CustomLevels[(int)count].location.ToString());
				Debug.Log(SceneIndex);
			}
			count++;
		}
		GUI.EndScrollView();
	}

I am not sure if i am doing something small wrong or what. this is the first time i have tried to work with scrollviews, so any help i can get would be great.

About GUI Scroll see my pregoing response. In your case in line 18

 scrollPostion=GUI.BeginScrollView(new Rect(Screen.width*0.05f, Screen.height*0.05f, Screen.width*0.75f, Screen.height*0.7f), scrollPostion, new Rect(0,0, Screen.width*0.7f, Screen.height*0.65f));

you set dimension on screen your scroll, how Screen.width0.75f, Screen.height0.7f. But dimension self scroll is Screen.width0.7f, Screen.height0.65f. Of couse, you don’t see your scroll. Simple change your dimension scroll, for example, little more your screen dimension of scroll:

 scrollPostion=GUI.BeginScrollView(new Rect(Screen.width*0.05f, Screen.height*0.05f, Screen.width*0.75f, Screen.height*0.7f), scrollPostion, new Rect(0,0, Screen.width*0.8f, Screen.height*0.75f));