Why are items in the store marked red?

I cannot figure out why I cannot purchase items in the shop in Survivor Squad. I have all the necessary ingredients, but the items in the list are marked red so I cannot buy them:

I even specifically emptied back packs of other stuff and only put sufficient supplies. In another attempt at this node, I was only able to buy one item, and I do not see any rhyme nor reason as to why I can or cannot do that.