Raycast and GUI question

I have been going through the forums and Google and can't seem to find a good answer for this. I have a tower defense game where after you click and place the tower you can click it again and a menu pops up, that all works fine, it uses raycasting and hit's. My issue is that within the towers menu I have a test button and when I try to click it the raycast shoot's through it and turns the menu off.

I have tried doing a state machine with a boolean and that didn't work and I also tried the rect.contains function that also didn't work. Does anyone have an idea of how to stop this then?

EDIT: Here is the code for the script I am trying to get it to work for. This is after the tower has been placed.

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 public class PlaceableBuilding : MonoBehaviour {
     
     
     [HideInInspector]
     public List<Collider> colliders = new List<Collider>();
     
     private bool isSelected;
     private string nameHolder;
     
     private bool overGUI = false;
     
     TurretProperties tp;
     
     Rect gRect1 = new Rect(0,200,100,50);
     
     
     void Start(){
         tp = GetComponent("TurretProperties")as TurretProperties;
         
     }
     
     void OnMouseEnter(){overGUI = true;}
     
     void OnMouseExit(){overGUI = false;}
     
     void Update(){
             if(Input.GetMouseButton(0) && !overGUI){
             Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
             RaycastHit hit;
             if(Physics.Raycast(ray,out hit)&&isSelected){
                 nameHolder = hit.collider.name;
                 }
         }
     }
     
     void OnGUI(){
         if(isSelected){
             if(nameHolder == "Tower1"){
                 GUI.Label(new Rect(0,0,100,30), nameHolder);
                 GUI.Label(new Rect(0,60,100,30), " " +tp.TowerDamage );
                 if(GUI.Button(gRect1," Plus 1")){
                     Debug.Log ("im clicked!!!");
                 }
         }    
             if(nameHolder == "Tower2"){
                 
                 GUI.Label(new Rect(0,0,100,30), nameHolder);
             }
             if(nameHolder == "Tower3"){
                 
                 GUI.Label(new Rect(0,0,100,30), nameHolder);
             }
         }
     }
     void OnTriggerEnter(Collider c){
         if(c.tag == "Building")    {
             colliders.Add(c);    
         }
     }
     void OnTriggerExit(Collider c){
         if(c.tag == "Building")    {
             colliders.Remove(c);
         }
     }
     
     public void SetSelected(bool s){
         isSelected = s;
     }    
     
 }