Hmm, you may not be able to sub it.
I was having no issues with a US subbed units in Canada. Well, I just changed to a new visa and guess what? I can't change my cc info online because my radio "address" doesn't match my real cc address. On top of that I can't change my radio address because it won't let me use a Canadian address on the US site.
I guess my only option it let it expire and register on the Canadian site?