How to use dynamic reporting periods in a trigger

[#1]

Hi Qlikview experts,

I want to show dynamic periods (Years)  in a Dashboard.

What I did till now.

- Made a variabele - Years_back. e.g input =2,Result = 2011 (in combination with Year (today()) function.

- Made a variabele - Years_forward. e.g. input = 3,  Result = 2016

In Settings

Sheet properties
Triggers.

On activate sheet add Action

Select in Field

- selected Field = Year

- search String used the function Valueloop

(= ValueLoop($(Years_back), ($ Years_forward) .

This does not work. Where did I go wrong?