No save button on discount page

-- HikaShop version -- : 2.3.5
-- Joomla version -- : 3.3.6
-- PHP version -- : 5.6

I want to make a temp discount on a category. But when I open up to choose the category there is no way to save.
The top button is missing.
Is this a bug?

If you click on a category in the explorer, it shows you the subcategories in a list below, from which you can select one ("Benyt").

Means that if you want to select the category "Workshops", first click onto its parent category "Online Butik" in the explorer. Then "Workshops" will appear in the list below, so you can click on either its name or the + in front of it to select it. The popup closes then without further action.

aha, thanks a lot