Ubuntu can't connect to my android's hotspot

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http://askubuntu.com – I'm a real newbie (and not a good English speaker...) I've tried to run Ubuntu from Live CD to check it. Ubuntu recognized my android's hotspot (I use android 2.1 with "Wifi Tethering") but wasn't able to connect to it. It's really a problem for me because I don't have any other internet connection. Do you know why? Thanks. (HowTos)