SiteOps, I already told you you'd need AttachCenter or something. You can view the valid attachment points in the Cutscene module (they're defined individually for each model, but all units have Origin and Center)
For the "attach" SOps to work you also need the actor you'll be attaching to, hence the "At" Term I also mentioned in my previous post. Behavior triggers automatically default to the unit that gains the behavior, but for Effects there may not be a valid unit linked to them. Best example: Psi Storm, the lightning field is always placed where the AoE cursor was, even if there's nothing in range. That's the "At Effect" scope.