There should be some eggs starting to appear at 24 weeks. Have you tried increasing their light hours? You can start increasing by about a half hour every 2-3 days, until they are getting 15-16 hours per day minimum. That may stimulate some production.
As mentioned previously, get them on laying pellets if you haven't already, they need the protein. Cut back on the treats.
As mentioned previously, get them on laying pellets if you haven't already, they need the protein. Cut back on the treats.