Index array is out of range (following H&S tut)

I have been trying to get this code to work for a while now, I am pretty new to this whole C# scripting and never really finished learning XML. My problem is with changing a material for the hair. I set up a specific mesh slot for the hair and somehow it just wont work. It constantly give me the "Index array is out of range" error. In the "Changing Room" scene it will change the hair colour but spews out the error constantly, in the "CharacterCustomization" scene it wont load any materials.

This is the code that is causing the problem

 private void ChangeHairMaterialGUI() {
         if(GUI.Button(new Rect(Screen.width * .5f - 95, Screen.height - 175, 30, 30), "<"))
         {
             _hairMaterialIndex--;
             ChangeHairMeshMaterial(CharacterMeshMaterial.Hair);
         }
         
         GUI.Box(new Rect(Screen.width / 2 - 60, Screen.height - 175, 120, 30), _hairMaterialIndex.ToString());
         
         if(GUI.Button(new Rect(Screen.width * .5f + 65, Screen.height - 175, 30, 30), ">"))
         {
             _hairMaterialIndex++;
             ChangeHairMeshMaterial(CharacterMeshMaterial.Hair);
         }
     }
     
     private void ChangeHairMeshMaterial(CharacterMeshMaterial cmm) {
         Material[] mats = pc.hairMaterialMesh.renderer.materials;
 
         for(int cnt = 0; cnt < ca.hairMaterial.Length; cnt++)
             mats[cnt] = ca.hairMaterial[cnt];
 
         //switch(cmm) {
         //        case CharacterMeshMaterial.Hair:
             if(_hairMaterialIndex > ca.hairMaterial.Length - 1)
                 _hairMaterialIndex = 0;
             else if(_hairMaterialIndex < 0)
                 _hairMaterialIndex = ca.hairMaterial.Length - 1;
 
             mats[(int)cmm] = ca.hairMaterial[_hairMaterialIndex];
         //    break;
         //}
         
         DestroyImmediate(pc.hairMaterialMesh.renderer.materials[(int)cmm]);
 
         pc.hairMaterialMesh.renderer.materials = mats;
             
 //        Debug.Log(mats.Length);
 //        Debug.Log("Wearing:" +pc.characterMaterialMesh.renderer.materials[2].name + " Should be wearing: " + ca.torsoMaterial[_torsoMaterialIndex].name );
 //        Resources.UnloadUnusedAssets();
     }

The main problem is in the line

 mats[(int)cmm] = ca.hairMaterial[_hairMaterialIndex];

Any help would be greatly appreciated as I have big plans in the works!