Biomes ins't generating

Hey, my friends and i have a problem with the better nether mod: the structures and ores are generating but not the biomes.

Please someone help me with that, and yes i've already reset the nether but nothing changed only vanilla biomes.

We first played in vanilla and then added mods but we didn't go to the nether in vanilla that might be why.

But still wierd that only structures and ores generate no biomes or mobs.