How can I know the IP address of a guy who sent an email using gmail.com to my yahoo mail?

I have chosen 'Actions' then 'View Full Header' of my yahoo mail account but the only IP address I could retrieve is 74.125.83.45, which is the US. However, the email was sent from another country! Is there another method to know the IP address of the sender? Because clearly, this is the wrong IP address!