Tailoring SpecializationFollow

I have a level 73 toon that has tailoring at 406. I would like to specialize in Mooncloth Tailoring, but haven't figured out how to do that. I go to the tailor specialist toons and see no option to learn the speciality. What am I missing? I even went to Bruner in Dalaran and had no luck.

Thanks

Going to Shatt will only give you the option of doing a Quest that will allow you to train for Shadoweave