Get order data when invoice is being create from admin

Question

How to get order data of which admin is creating invoice.

I am using this code

observer call on config.xml

<events>
<sales_model_invoice_pay>
    <observers>
       <Karmick_Refer_Model_Observer>
          <type>singleton</type>
          <class>Karmick_Refer_Model_Observer</class>
          <method>changeStatus</method>
       </Karmick_Refer_Model_Observer>
   </observers>
</sales_model_invoice_pay>
</events>

Observer.php

<?php
class Karmick_Refer_Model_Observer{
public function changeStatus(Varien_Event_Observer $observer){
    $due = $observer->getEvent()->getInvoice()->getOrder()->$order->getBaseTotalDue();
    Mage::log($due.'@@@');

}
}
?>

but it seems that nothing is being printed on log

Answer 1

Try switching your event to sales_order_invoice_pay