In response to our new friend from Korea, Song, chi-hun:
Yes, there certainly could be a difference in the frequency at which your keyfob transmits. Most US keyless entry remotes — including most GM remotes — transmit at a frequency around 315 mHz. Many GM vehicles sold in overseas markets, however, use a high-frequency keyless entry system that transmits at 434 mHz. However, if you have a US vehicle and a US remote, I am not sure why the part would not work, unless it is defective or has a bad battery. Possibly, the scan tool used by the Korean dealership has different software than one would in the US. I cannot speak to that. Please note, though, Remotes Unlimited sells only new remotes on our website. We do not sell re-cased or reconditioned keyfobs as many websellers in the US do.