GUI Matrix problem only on iOS

Hi all,

i get this error in the xcode log:

 Ignoring invalid matrix assinged to GUI.matrix - the matrix needs to be invertible. Did you scale by 0 on Z-axis?

This is the code I used:

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 public class GUISizer {
     
     static float  WIDTH = 720f;
     static float HEIGHT = 1280f;
     
     static List<Matrix4x4> stack = new List<Matrix4x4> ();
     
     static public void BeginGUI() 
     {
         stack.Add (GUI.matrix);
         Matrix4x4 m = new Matrix4x4 ();
         float w = (float)Screen.width;
         float h = (float)Screen.height;
         float aspect = w / h;
         float scale = 1f;
         Vector3 offset = Vector3.zero;
         if(aspect < (WIDTH/HEIGHT)) { //screen is taller
             scale = (w/WIDTH);
             offset.y += (h-(HEIGHT*scale))*0.5f;
         } else { // screen is wider
             scale = (h/HEIGHT);
             offset.x += (w-(WIDTH*scale))*0.5f;
         }
 
         Debug.Log ("Offset: " + offset + " aspect " + aspect + " scale " + scale);
 
         m.SetTRS(offset,Quaternion.identity,Vector3.one*scale);
         GUI.matrix *= m;
     }
     
     static public void EndGUI() 
     {
         GUI.matrix = stack[stack.Count - 1];
         stack.RemoveAt (stack.Count - 1);
     }
 }

Everything works fine on PC and Android.