Trevenant & Dusknoir GX Attack Bug

When I use the GX attack on this card, it does it incorrectly.

Pale Moon GX

At the end of your opponent's next turn, the Defending Pokémon will be Knocked Out. If this Pokémon has at least 1 extra Psychic Energy attached to it 

(in addition to this attack's cost)

, discard all Energy from your opponent's Active Pokémon. 

(You can't use more than 1 GX attack in a game.)

When I have an extra energy, it dumps the energy after I attack, but it doesn't actually knock out the Defending Pokemon at the end of my opponent's next turn.