Love Potion

Mildred and Enid are preparing a love potion to reconcile their singing teacher, Miss Bat, with her love, Mister Rowan-Webb.
The potion is accidentally served to the entire teaching staff, unleashing romantic chaos.

But why doesn't the potion work on Hecate Hardbroom?

A/N: I'm French, so I apologize in advance if there are any mistakes in this fanfiction !
The French version is on my profile.