Error: Expression denotes a `X', where a `Y' was expected

Hello,

I don´t understand why these erros are comming up. Is the last code line.

-->(39,49): error CS0119: Expression denotes a type', where a variable', value' or method group' was expected

-->(39,31): error CS1502: The best overloaded method match for UnityEngine.GUI.HorizontalSlider(UnityEngine.Rect, float, float, float)' has some invalid arguments -->(39,31): error CS1503: Argument #1' cannot convert object' expression to type UnityEngine.Rect'

I am a newbie, so please answer with some explanation and code or I will not understand, thank you.

 using UnityEngine;
 using System.Collections;
 
 public class BotonesMenu : MonoBehaviour {
 
     public float puntMax;
     float velChange;
 
 
     // Use this for initialization
     void Start () {
         puntMax = 2000.0f;
     }
     
     // Update is called once per frame
     void Update () {
         
     }
     
     void OnGUI () {
         // Make a background box
         GUI.Box(new Rect(Screen.width/2 - 150,10,300,300), "Menu");
         
         // Make the first button. If it is pressed, Application.Loadlevel (1) will be executed
         if(GUI.Button(new Rect(Screen.width/2 - 40,40,80,20), "1 jugador")) {
             Application.LoadLevel("PrimerEscenario-GuardadoManualmente");
         }
         
         // Make the second button.
         if(GUI.Button(new Rect(Screen.width/2 - 40,70,80,20), "2 jugadores")) {
             Application.LoadLevel(2);
         }
 
         GUI.Label (new Rect (Screen.width / 2 - 30, 120, 60, 20), "Opciones");
 
         GUI.Label (new Rect (Screen.width / 2 - 90, 150, 180, 30), "Puntuacion para ganar: "+puntMax);
 
 
         puntMax = GUI.HorizontalSlider (Rect(Screen.width / 2 - 100, 175, 200, 10), puntMax, 0, 50000);
     }
 }