Vampiric Embrace and Mana Burn

Hey, Nostalrius community! I was playing WoW yesterday with my brother who plays a priest, when he asked me why doesn't his mana burn (which causes shadow damage) heal him with vampiric embrace? I was wondering if this was just a server bug, (since only patch 1.9) hasn't been implemented yet or if this was just something that was overlooked by Blizzard? Your thoughts and opinions are welcomes here! Thanks! 
