I have make custom module in which I have make observer file. the observer file calls successfully after 'customer_save_after' event. Now I want to write some custom code on observer file. For this I want to get last save user id. for this I am using following code. "echo $id = Mage::getSingleton('customer/session')->getCustomer()->getId();" But nothing is print by this. How can I get the customer id here?