My N15 (llke most modern Nacras) has an S shaped hook that hooks on a ring that's on a wire swaged on the forestay. It's a fiddly setup; for some reason it mostly worked when I got the boat 6 months ago. For unknown reasons, it now doesn't want to hook, and if we managed to get it to hook, it then will not unhook.
It's a devilish device. But sometimes there's a trick to these (there are tricks for the ring and hook on the mainsails...)
Do you use a boat with this setup? have you sorted it out?