connecting ATV to older 2004 or 2005 Panasonic model TH-42PX20 plasma TV

I have a 2004 or 2005 Panasonic model TH-42PX20 plasma TV that I am trying to use with Apple TV ( 2nd generation). The TV has the HDMI port but cant access the HDMI input mode. The sequence of modes accessible from the TV/VIDEO button should be TV-Component 1- Component 2 - HDMI - Video 1 - Video 2 - Video 3, but I only get TV and Component 1. Any idea how I can access the HDMI input mode to access ATV screen?