Well..... is she a pullet who is just starting to lay or an older bird that has been laying but the shells have gone rubbery? Causes are 1.) new to laying and the pullet is misfiring but it will straighten out. 2.) she is calcium deficient and doesn't have enough to build a decent shell - supply oyster shell to correct that. 3.) some birds - rare but it happens - can't build a decent shell. I'm sure I missed a bunch of other scenarios - but maybe this will help you.
& What are you feeding them? Are you providing free choice oyster shell? ETA: I keep this bookmarked for easy reference, you may find it helpful http://www.thepoultrysite.com/ourbooks/1/egg-quality-handbook/
