Binding a key directly to a companion

[kraftman]

I'm trying to allow users of my addon to directly bind keys to companions.

SetBindingSpell("key", "spell name") doesn't seem to work, SetBindingSpell("key", "spellID") seems to set the spell properly, in that GetSpellTexture(GetBindingAction("key")) returns the correct texture for the spell, however pressing the key doesn't call the companion.

Is there another way to do this that doesn't involve either creating a macro, or creating a button?