I made "honeycomb" (otherwise known as hokey-pokey, not real honeycomb) using this recipe: http://www.nigella.com/recipes/view/hokey-pokey-36
It tastes delicious but it is supposed to be crunchy / cripsy (like the inside of a Cadburys Crunchie bar) but it actually came out really sticky, like a soft toffee.
Is this likely to be due to overcooking, undercooking, something else? How can I make sure it comes out crunchier in future?