title: Asigning postback trigger to control inside ListView
body: <p>I have a ListView inside UpdatePanel. Each row of ListView contains some buttons. One button invokes method which sends file (Response.WriteFile(...)) so it should be treated as post back trigger and my question is how can I achieve this? When I put ID of this button into triggers section of UpdatePanel I get error "(...) control was not found(...)". 
  Data is binded into ListView only during first page load</p>