Let's start with the basics: what makes you think she's gravid? If it's because you put her in with a male, that doesn't necessarily mean she's gravid. She could have not been ovulating at the time. She could have been too young. Also, some female geckos just don't lay. I bred leopard geckos for 13 years and some other species for nearly that long and there were some geckos who never laid. If it's your first gecko, it's also possible that breeding isn't a good idea yet, but I'll leave that to you. If you have any more idea about what you're confused about, we'd be happy to try to help.