Sort order not used on list

Hello,

when using sort order in list (like tikets screen), items are sorted by alphabetic order, not using order define in list.

ie : i want to sort tickets by priority to export list in XLS. If i use sort in criteria selector, it sort tickets in order Faible - Haute - Moyenne (alphabetical) not with order set when i create the priority list (Faible (order 10), Moyenne (order 20), Haut (order 30)).