Problem using a level NPC that's joined to a class

[Sp_lit]

Hey there!
This is me and my friend's first attempt at GS2. This is what we've got so far. We're just wondering; are we on the right track here? We have encountered some problem with triggeraction when trying to trigger serverside from clientside, in a level NPC.

Any ideas or suggestions on what to improve or totally change?
In case the aweful script does not tell; we're trying to create a shop system..or something closely remote to one...

Help is very much appreciated, thanks!

Class:

PHP Code:

function onActionBuyItem()
{
  player.rupees = 0;
}

function onCreated() {
  this.setShape(1, 32, 32);
  this.dontblock();
}

//#CLIENTSIDE
function onPlayerTouchsMe()
{
  new GuiBitmapBorderCtrl("Shop_Window") 
  {
    this.profile = GuiBitmapBorderProfile;
    this.width = screenwidth / 2;
    this.height = screenheight / 2;
    this.x = screenwidth / 2 - this.width / 2;
    this.y = screenheight / 2 - this.height / 2;
    this.canmove = false;
    this.canresize = false;
    this.makefirstresponder(true);
    
    new GuiButtonCtrl("Shop_Button")
    {
      width = 100;
      height = 40;
      x = Shop_Window.width / 2 - this.width / 2;    
      y = Shop_Window.height - this.height - 10;
      text = "Buy";
    }
        
    new GuiShowImgCtrl("Shop_Item_Fireball") 
    {
      x = 20;
      y = 20;
      width = 60;
      height = 60;
      
      this.imageselected = "split_fireball_selected.png";
      this.imagenotselected = "split_fireball.png";
      this.image = this.imageselected;
      
      this.price = 20;
    }
    
    new GuiShowImgCtrl("Shop_Item_Sword") 
    {
      x = Shop_Item_FireBall.x + Shop_Item_Fireball.width + 20;
      y = 20;
      width = 60;
      height = 60;
      
      this.imageselected = "split_sword_selected.png";
      this.imagenotselected = "split_sword.png";
      this.image = this.imagenotselected;
      
      this.price = 30;
    }
  }  
  this.listofitems = {Shop_Item_Fireball, Shop_Item_Sword};
  this.itemselected = this.listofitems[0];
}

function onMouseDown()
{
  if(!((mousescreenx in |Shop_Window.x, Shop_Window.x + Shop_Window.width|)
      &&(mousescreeny in |Shop_Window.y, Shop_Window.y + Shop_Window.height|)))
  {
    Shop_Window.destroy();
  }
}

function Shop_Button.onMouseDown()
{
  triggeraction(this.x + 0.5, this.y + 0.5, "ButItem", null);
}

function Shop_Button.onMouseUp()
{
  Shop_Window.makefirstresponder(true);
}

function Shop_Item_Fireball.onMouseDown()
{
  for(i = 0; i < this.listofitems.size(); i ++)
  {
    this.listofitems[i].image = this.listofitems[i].imagenotselected;   
    if(this.listofitems[i] == Shop_Item_Fireball)
      this.itemselected = this.listofitems[i];
  } 
  Shop_Item_Fireball.image = Shop_Item_Fireball.imageselected;
}

function Shop_Item_Sword.onMouseDown()
{
  for(i = 0; i < this.listofitems.size(); i ++)
  {
    this.listofitems[i].image = this.listofitems[i].imagenotselected;   
    if(this.listofitems[i] == Shop_Item_Sword)
      this.itemselected = this.listofitems[i];
  }
  Shop_Item_Sword.image = Shop_Item_Sword.imageselected;
} 


NPC:

PHP Code:

this.join("shopkeeper");