Nice to hear that the issue is resolved.
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If you use the contact form again, let us know when you did it so we can look in the spam folder as well.

Hi
Now it works on the website I'm making. Only when I select :
- "Inherit from the category" in the parameters of the menu link to a K2 category
- "ordering" everywhere for all the categories and sub-categories

But I think I will be back on this forum for my next website with K2 (or earlier), because I tried (and re-re-retried) exactly the same thing on a test site ... and the ordering I make for the items in the K2 admin is not applied in frontend ...

Thanks for you help.

Are all the extensions and Joomla! on their latest versions?

On both sites (new site and test site) : Joomla 3.4.1 + K2 v2.6.9