update panel in master page and asyncpostbacktrigger in content page

I have a cart in master page that this cart is inside update panel.
In my content page I have a listview that in this listview exist linkbutton for add product to my cart.
I want to add product to cart using these linkbuttons without refresh, and cart is updated. I have this code in my content page:
`protected void Page_Init(object sender, EventArgs e) { UpdatePanel up = (this.Master.Master.FindControl("UpCart")) as UpdatePanel;

    AsyncPostBackTrigger trigger = new AsyncPostBackTrigger();
    trigger.ControlID = lvNewProducts.UniqueID;
    trigger.EventName = "ItemCommand";
    up.Triggers.Add(trigger);



}`

but my page is refreshed when I click in linkbutton.
Please help me!