Greetings protein adhesive fans.  Quiz time.  Any clue why fish glue
wouldn't adhere well to zephyr skin?

I'm gluing up pouches on a Lauter, and fortunately had only done ten
of them before I started checking.  The glue had cured overnight, but
when I tugged a corner of the zephyr skin, it peeled off quite easily.
I've switched to hot hide glue for the job.

Thanks in advance.
Skip Downing, in snowy New Hampshire