Wrong IP address detection?

Hi,

I have the premium free shipping plugin, and I set the General Settings -> Detect IP selector to Enabled.
I have free shipping defined only for the US, and thus the free shipping bar is supposed to appear only when a customer has a US IP address. Well, I have checked and no matter from which country you visit my store, the free shipping bar will pop-up and that misleads customers from other countries.

Please advise.

Thank you,