How to move a button from shoppingCart to Shipping step

[suwanchaic]

Just install print quotation addon and after press cart then display a new button 'print quotation' on the web store in the first step => Summary, given code like this:

!$this->registerHook('shoppingCart')
and ....

function hookShoppingCart($params)
{
return $this->display(__FILE__, 'printquotecarttopdf.tpl');
}


I try to move the button 'print quotation' to step => Payment , modify the line like this:

!$this->registerHook('payment')

and change the line...

function hookPayment($params)
{
return $this->display(__FILE__, 'printquotecarttopdf.tpl');
}

But it's not work. Do anyone know how to hook the button???