I tested harliquin head/frame... Apparently Harliquin head is the root source of why he isn't casting (Harliquin Head doesn't cast) (Someone should report this). If you switch to Stormwaker head + Harliquin frame, he casts just fine. By the way, Dread spikes/Absorb Attirbute (Dark manuevers) are on BLM Head frame, Addle (Fire manuevers?) is on BLM/RDM, Dispel (Dark manuevers) on Stormwaker Head, Stoneskin/phalanx Stormwaker Head only, Haste on Stormwaker/Soul Soother.
*Also cool side note:
Harliquin Body + BLM Frame is the new DRK frame. He uses Dread Spikes/Thunder V and down spells/Bio/Drain/Aspir/Absorb Attri/etc.
He tanks extremely well too. I soloed Awahando with him in Abyssea.