If I were you I would leave Camponotus for now an have a different species instead. but if you do try them again try a different set-up and make sure their nest is very warm and humid. my nest: 26C about 70% humidity
This is why i dont keep ants in sand or loam... or anything else.. there is too many risks... Ive lost colonies keeping them like this and I will not do it again.. When they are in just a ytong they do fine.. all they need is ytong and an outworld to forage...