If you’ve made your syrup, baked your snack mix, let it cool and it’s still soggy, the most likely reason is that you didn’t cook the syrup to a high enough temperature.  If you don’t cook the syrup to 235 degrees F, there will still be too much water content and the sugar will not reach the correct soft-ball stage.  Make sure to use a candy thermometer to check the temperature as the syrup cooks.