"Taken" indicates that the spell is taking effect, when in this case it is not. Calling taken when you are not affected by a spell is misleading and leads to holds being called when they should not be necessary.
Some situations where a PC would call "no effect" to a spell (a Spell Shield or Reflect Magic will still be set off) are as follows. This list is by no means complete; there may be other situations where a PC may call "no effect" to a spell. These are only the most common.
Enflame, Shatter, Destroy, or Disarm when an invalid item is called.
Enflame or Disarm when no item is in hand.
Shatter or Destroy when used on an indestructible item.
Control, Help, Turn, Harm, or Destroy Undead, if you are not undead.
Create Undead if you are not dead.
Any spell except Life or Create Undead if you are dead.
Any spell except Dispel Magic if in a Prison.
Light, Circle of Power, Wall of Force, Wizard Lock, Lesser Investment, or Ward, as they cannot target a person.
Life, if you are not dead.
Solidify, if you are not gasseous.
Earth Storm, if you are alive.
Chaos Storm, if you are undead.
Shun or Repel, if you become your own target.
In order for one command to override another, the new command must take affect.
You cannot be the target of your own shun, so you would call no effect to your own Shun.
Reflect Magic does not change the originating caster, so you would call no effect to a reflected Shun.
-Dan