Q8 - D&D 4th ed.

How does the Eladrin racial resistance to Charm effects manifest in combat against monster abilities/powers with the Charm keyword?

I ruled on the fly that the player (running an Eladrin character) had to make an immediate saving throw at +5 to avoid the invisibility effects of Eyebite. She failed the save and so the warlock became invisible to her. Did I screw it up?