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It sounds like you have a Galaxy S phone, installed the Kies software on your phone, and it doesn't recognize your phone.
One thing you might want to do is disconnect your phone from it's USB connection to the computer, uninstall the Kies software, reboot the computer, install the Kies software once again, reboot the computer again, and then connect the phone to the USB cable that's connected to the computer. If that doesn't work try connecting the USB cable to a different USB port on the computer.