Green jack-o-lantern?

I planted jack-o-lantern for the first time and the fruit is now a little smaller than a football. It is DARK GREEN!!! Is this normal? I believe you can get strange squash from cross pollination but the seeds were bought new and cross-pollination problems occur if you keep the seeds from the year before, if I remember rightly? Is it that the fruit will turn orange at maturity or is it more likely that I mixed up the labels with something like olive squash or green hokkaido squash?