you're using DHCP but can you actually see an IP address, subnet mask and default gateway when your accessing the network tab in the settings? If 'IP' is assigned and you can't access the internet make sure your proxy settings are correct.

If IP isn't assigned make sure you've entered the correct SSID, encryption settings, proxy settings and set the device to 'Use DHCP'. If no IP is assigned check you Wireless Access Point. Is the range of IP addresses limited (on some access point ranges can be set).

You can also reboot the device and press the 'Channel +' button until you see 'Manual Configuration' screen. You now can set all settings + boot + try the net.