Why won't my ground beetles mate?

[invertebrateguy]

So i am keeping a species of ground beetle called carabus granulatus.
I have around 5 to 7 of them that i am trying to mate but they just won't.
So if anyone has advice i can use to make them mate i would appreciate it.
https://en.wikipedia.org/wiki/Carabus_granulatus

 

[Ultum4Spiderz]

I can’t seem to find anything on them I’m trying to breed mealworm beetles can’t see any eggs yet so I’m not having luck either .

Carabus granulatus | uk beetles

www.ukbeetles.co.uk