Problems Summoning Mephasm -=Spoilers=-

[Vincevaugn]

Hey guys, I'm currently in the begginning of Act III and while trying to summon mephasm I've encountered some problems. I'm pretty sure I'm doing everything correctly - using the right materias, having the right feat on Sand and using the correct spell Darkness on the magicians workbench near the summoning circle - After reading some other threads regarding this part of the game I may have identified the problem. Ammon Jerro won't give me a quest to summon Mephasm, only the recipe (Scroll) for the gold filligram charm. Without the quest, trying to craft the focus seems to be impossible since I get no response whatsoever when trying to craft it (Not even failure ones).

I'd really like to summon this guy and I'd really appreciate if you guys could help me solving this problem.

Thank you!