I've been trying to catch a Nincada in the bug catching contest in Heartgold, but it seems they're incredibly rare. On Serebii an Bulbapedia, it says 20% rate for a Nincada. However, they're really hard to bump into. I finally bumped into one today, but it was too low level for me to use. But even then, that's the only Nincada I've ever seen. And no joke, I saw Pinsir and Scyther, who only has 5%, at least 10 times each before meeting just one Nincada. Did I do something wrong? Why is it so damn hard to find a Nincada?