Sorry to hear that, this chicken raising "hobby" can be frustrating at times. My girls are all older (got them from an auction, I don't suggest that route for newbies... it's been one challenge after another *sigh*). The only thing I can suggest is to add oyster shells, if you're not already. I give my girls about 1/2 cup every morning spread over their breakfast. I also give them about a cup of yogurt to share every other day. I also read in this thread to chop up some kale to improve shells. If there's no shell at all after trying some calcium infused treats, then maybe there is a problem with her "system"?! I'm new to all this, but I know you can find a LOT of great info on here and the people are fantastic about giving advice!
Good luck