My server keeps crashing because of some weird problem

I'm trying to start a modded Pixelmon server my friends and I can play on. I've set the server software to Forge, and I've downloaded the mod Pixelmon Generations. Whenever I try to start the server, however, it crashes and in the logs it gives me an error saying that the mod "Biomes O' Plenty" is missing, and that it requires forge. It then tells me to install a version of forge that I can't even install, being 14.23.5.2768. What's more, I haven't even downloaded the mod Biomes O' Plenty, and when I checked the mods folder for the server, it wasn't even there. It might just be because it's a part of the Pixelmon Generations mod, but I have no idea what to do.