Unable to complete Seal of Ascension Quest

[Lastr]

http://i.imgur.com/6Q1q7cZ.jpg

I am unable to complete the final quest for the UBRS key - Seal of Ascension. I place the Unforged Seal of Ascension on the ground in front of Emberstrife and pull him, then bring him to sub 10% (He was currently 8%) in the photo. Once I try to use the Orb of Draconic Energy I get an "invalid target" message.

I have already tried different tanking spots and methods and have had to abandon and re-accept the quest to replenish the charges on the Unforged Seal of Ascension, yet despite what I try or do I cannot MC to complete the quest.

[Lastr]

Bump. After speaking with several people who have completed the quest - they have confirmed the Mind Control does NOT work, and the way they have unanimously completed the quest was by having Emberstrife use flame breathe on the Unforged Seal. I have tried this six times with no luck.

Edit: grammar

Update: I was able to complete the quest, I dropped the Unforged Seal when the dragon was at 30% and instantly had the quest completed.