Spell ala mass

I've gotten my mass invis spell to work, with Wisp casters and such, but although the bulk of the spell does work, the Wisps aren't going away, despite the 2 actions that would remove the wisp. The first method removes the unit variable that the wisp is attached to, and the second method removes all units in a region (where the wisp is). Does anyone know how to remove the wisps this trigger creates?


Events

Unit - A unit Begins casting an ability

Conditions

(Ability being cast) Equal to Crossroads Fog

Actions

Cinematic - Fade out and back in over 3.00 seconds using texture Haze And Fog and color (50.00%, 50.00%, 75.00%) with 25.00% transparency
Unit Group - Pick every unit in (Units within 512.00 of (Position of (Casting unit))) and do (Actions)
Loop - Actions
If (All Conditions are True) then do (Then Actions) else do (Else Actions)
If - Conditions
((Picked unit) belongs to an ally of (Owner of (Casting unit))) Equal to True
Then - Actions
Unit - Create 1 Caster R1 for Player 4 (Purple) at (Random point in ACastZone <gen>) facing Default building facing degrees
Set CSCaster[0] = (Last created unit)
Unit - Order CSCaster[0] to Human Sorceress - Invisibility (Picked unit)
Wait 0.01 game-time seconds
Unit - Remove CSCaster[0] from the game
Else - Actions
Wait 1.00 game-time seconds
Unit Group - Pick every unit in (Units in ACastZone <gen>) and do (Actions)
Loop - Actions
Unit - Remove (Picked unit) from the game

Try something like this...
I'm not sure exactly why your trigger doesn't work, but I know for a fact this one does. It's a modified version of one of my spells.


Untitled Trigger 001
Events
Unit - A unit Begins casting an ability
Conditions
(Ability being cast) Equal to Mass Invis
Actions
Unit Group - Pick every unit in (Units in (Region centered at (Position of (Casting unit)) with size (512.00, 512.00)) matching (((Owner of (Matching unit)) is an ally of (Owner of (Casting unit))) Equal to True)) and do (Actions)
Loop - Actions
If (All Conditions are True) then do (Then Actions) else do (Else Actions)
If - Conditions
((Picked unit) is A structure) Equal to False
((Picked unit) is alive) Equal to True
Then - Actions
Unit - Create 1 Wisp for (Owner of (Casting unit)) at (Position of (Picked unit)) facing Default building facing degrees
Unit - Order (Last created unit) to Human Sorceress - Invisibility (Picked unit)
Unit - Add a 2.00 second Generic expiration timer to (Last created unit)
Special Effect - Create a special effect attached to the overhead of (Picked unit) using Abilities\Spells\Human\HolyBolt\HolyBoltSpecialArt.mdl
Special Effect - Destroy (Last created special effect)
Else - Actions
Do nothing