It doesn't let me make weakness potions but it does let me make other potions.
What I expected to happen was...:
Describe what you thought should happen here

What actually happened was...:
What I thought would happen was that I would have potions of weakness.
Steps to Reproduce:
1. First make a rare potion with Nether Wart.
2.with those potions put fermented eye
3. I don't get the potion,