Forum:Evocator & Archfiend Gilfer Combo

Ok I just needed some assistance with the combo above and I need to know if this works or not? :D

Evocator Chevalier Effect:This card is treated as a Normal Monster while face-up on the field or in the Graveyard. While this card is face-up on the field, you can Normal Summon it to have it be treated as an Effect Monster with this effect: ● You can send 1 face-up Equip Card you control to the Graveyard to destroy 1 card your opponent controls.

Archfiend of Gilfer Effect:When this card is sent to the Graveyard, you can activate its effect. You can then equip it to a monster on the field, and this card will be treated as an Equip Spell Card that decreases the ATK of the equipped monster by 500 points.

Now I came up with this combo on my own and started using it in duels with my friends.. but when I played the Yugioh game for the PSP it had told me I'd missed my chance? So I'm quite confused could someone tell me why this has happened thx for the help :D