In WoW why won't my trainer work?

I'm an orc warlock in Word of Warcraft, and i've leveled up to three new spells. When I go to my spellbook it says to go to your trainer. Whenever I go to the trainer in my original home town, I right click to train with him. When the training menu comes up, it's totally blank. I checked the filter and it said both available and unavailable spells should be showing up. Why can't I train the spells?