During my level 48 fire quest for the Fire Dragon, Mavra Flamewing's tower in Dragonspyre (Plaza of Conquests) won't work. It's a boss/dungeon room, and the 4-person join pad doesn't work for me. I can't figure out what to do, as I've tried to restart my game, change servers, etc.
It sounds to me like you aren't far enough into the Dragonspyre storyline to unlock her yet. She is unlocked during one of the quests in the Plaza of Conquests given by Laszlo Starblade. She gives a lesson on shields and another gives a lesson on traps. You cannot earn school quests in areas that you haven't accessed yet. Do some questing in DS to catch up.