Porting Across Listings from UK to US

Hi Guys

I run a private label brand on Amazon UK. We are now expanding into the US and first port of call is Amazon US.

I am trying to port over my products from Amazon UK, by entering the ASINs in the catalog lister.

Only 6 of my 12 ASINs appear when I search them. This means that only 6 will carry across, correct?

So for the 6 ASINs not found, what are my options? Do I just have to start from scratch on them? I would very much like each to port across as each ASIN has a good sales history

Anyone got any experience of this?

Thanks in advance!