Promote item lifecycle with method on button in Aras 10

In Aras 10

I have an Item with a simple lifecycle (Active - Closed)
I want to create a button on the form, where I can promote the lifecycle to Closed by a click.
I have working methods for saving and unlocking the item, but I would like to have it promoted also.

I've created a metod (Javascript, client side) with the following two lines:
 
var myItem = document.thisItem;
myItem.promote("Closed", "Promoted by Aras");

I've then added this method to a button with "onClick" (Field Event)

BUT nothing happens When i click on the button?
Does anyone have a working method for this?

Thanks/Benny