This is because all of the Knowledge skills are trained only, so normally, if you have no ranks in that skill, even though you have a racial bonus to that skill, you can't make checks for that skill. Try creating a Human Druid - you'll see that even though that character has Know:Nature as a class skill, with a bonus from the class, you don't actually get to use that skill without any ranks.
If one of this race's special abilities is to make that skill usable untrained, enter the following in the same script that's applying the racial bonuses:
Code:
perform hero.childfound[skKnowNat].delete[Helper.TrainOnly]
If the race has some Hit Dice, and therefore has some skill points to spend, and you want to dictate that all members of this race take ranks in Knowledge:Nature, add this to that script:
Code:
#skillinnate[skKnowNat] += 1
(or += more than 1 - whatever you want, liited by the number of Hit Dice it has)