Why doesn't my MacBook air connect to wifi in a different country?

Question

I've moved from France to Australia and my MacBook Air and iPod won't connect to wifi, but my iPad will.
Why is this - I've tried to change the settings but no luck.

Answer 1

i recently changed the carrier
Contact the carrier to make sure you imputed all their information correctly. 
Read your routers user manual, call their customer support department or visit their website for further support.
Other things to try - Change your router channel.  Sometimes this is all you will have to do.
Power cycling the router.  Read the router's user manual or contact their tech support for instructions.
System Preferences/Internet & Network/Network
Unlock the padlock
Locations:  Automatic
Highlight Airport
Click the Assist Me button
In the popup window click the Diagnostic button.
System Preferences/Network- Unlock padlock.  Highlight Airport.  Network Name-select your name.  Click on the Advanced button.  Airport/Preferred Networks-delete all that is not your network.
Place a check mark next to "Remember networks this computer has joined."  Click the OK button and lock the padlock.  Restart your computer.
http://support.apple.com/kb/TS1920 Mac OS: How to release and renew a DHCP lease
No internet connection (wireless)
Check to see if an extra entry is present in the DNS Tab for your wireless connection (System Preferences/Network/Airport/Advanced/DNS).
Delete all extra entries that you find.
Place a check mark next to "Remember networks this computer has joined."
Other resources to check into:
Mac OS X 10.7 Help: Investigate your network connections
Mac OS X 10.7 Help: Check the status of your network connections
How to diagnose and resolve Wi-Fi slow-downs
Pv6 troubleshooting
What Affects Wireless Internet?
Solutions for connecting to the Internet, setting up a small network, and troubleshooting