[Plugin: Amazon Affiliate Link Localizer] IP address redirects to wrong country

Pete
I love this plugin. However recently I started using HMA VPN. So all of a sudden when I access my site-my IP is different from my regular ip. TO my shock when I hover on top of my amazon links they are showing UK links even though my IP address is a New Jersey IP. So this is concerning as it tells me that someone clicking from New Jersey is being take to the UK site when they are looking for US site.
Have you seen this problem before – of the plugin misreading the country to which a particular IP address belongs to?

http://wordpress.org/extend/plugins/amazon-affiliate-link-localizer/