Help with Gelish on a client

[slm1234uk]

I've been doing this client for some months now. She has very weak thin nails so normally lasts up to two weeks before. I use Gelish Structure gel under the colour.

The last two treatments two of her nails have peeled off within a weak even though I do the same each time and they are colours she has had before.

Any advice as to how to prevent this from happening?

Thanks!