Luxury Trading

Hi

Noobie, but I have searched for an answer - apologies if duplicating.

Playing on Prince and higher, I am confused over the trading of luxuries, whereby some opposing civs seem to vary the luxuries available to trade, along with my luxuries available. Just now, I tried to trade with Spain (friendly) - I had 6 copper (and a few others) and Isabella had no luxuries - so no trade. One turn later, Germany declares war on me, breaking a number of existing luxury trades. So I go back to Isabella who now has several luxuries available to trade, but I seem to have none.

WTF?

All help appreciated

If she acquired the luxuries you have by other means, they won't show up on the list of luxuries you can sell.