BC Credit for Amazon Purchases

I followed the Amazon.com link and I think I lost the BC referral (tag=dopplerpress-20 in the URL) as soon as I left the "Books" section of Amazon. It stayed missing if I clicked "Best Sellers" and then clicked "Books" again. Does that mean that BC gets no commission if I search out a teapot (for instance) even though I entered via the link from BC?

Sara