Problems with variants

Hi - I am newbie here. Yesterday I installed HikaShop and tried out if its comfortable software for me. Now I ve a problem: I can't manage variants because it don't let me create some.
I created characteristics and categories already. Adding category is no problem, but when I try adding characteristics there always shows up: Please make a selection from the list. I did but selection didn't worked. I noticed that the "underlining" doesn't show up as it does in categories i.e.
Please - someone knows what to do?

And: When it's working that variants thing ... how many characteristics I can combinine? I need for my products that customers can choose 1. size, 2. year, 3. month, 4. empty field for telling me a day or something like that. Is that possible?

Thanks
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