Problems with adwords conversion tracking problems

I have problem with adwords conversion tracking:

My project domain A is informational products site, and promoted through adwords. Domain A contains links to products checkout site domain B. So now I want to track sales and lead conversions in adwords.

This is a scenario – PPC -> Domain A -> Domain B (checkout).

I've added sales conversion tracking code on domain B.

Now as I tested by my own adwords is tracking only about 50% conversions, and remarketing tracking is even worse – about…

Problems with adwords conversion tracking problems