All my products are out of stock. Why?

We are selling classical music – digital download as well as physical CDs sent by post. Entering the product page for some CD you will overall have the oppotunity to choose between these options: CD, Flac or MP3. Make your choise and you will se that every produckt is “Out of stock”.
In the control panel > Products > Product data > Inventory my default leaves “Manage stock?” uncheked, but even if I check it and enters “Stock Qty = 1000” and “Stock status = In stock”, the result in the browser is the same: “Out of stock”.

What am I doing wrong?

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