I have activate "show shipping". But it's shown always as "Free" at all items after importing/updating my watchlist! Why???

Shipping fee is not always reliable especially when seller offers different shipping methods or shipping is calculated dynamically.

Also, you see the "free" shipping because it listed as free in the US probably. If you did not change your settings in Profile, then it's set to check US by default.

Next time, please always include the item number if your question is item specific.