Unfortunately, I have limited information on the boxes and peripherals you're using, but the AV port should work when used with the Wii and DVD player. Does just moving the switching box with the attached peripherals work? Or are you trying to use different inputs for each device?
Have you tried editing the name of the AV input with the device attached? Moving through the options in editing the name may bring the picture up on the screen, and gives options for different AV inputs.
I have just had Foxtel IQ2 installed, and as such, now a HDMI cable from the Foxtel box to the back of the tv - no problem there.
Prior to IQ2, I only had Foxtel IQ, which was connected using white, red & yellow male to male cables. I used a switching box to go between Foxtel, Wii & DVD which was connected using the AV port on the left hand side - again no problem, a cheap solution that worked well for me.
The problem I have now is that the tv wont recognise anything in the AV point, even when i go through the menu and refresh. As such, I cant use the Wii or play dvds. Ihave also tried the component ports to no avail, even taking out the HDMI cable. Can anyone assist with info how to sort this out? I need the dvd to test the surround properly with Top Gun