Removing Abilites on Cast

I'm at school right now, but it's only free time I had to write this.
I'm working on a triggering system to develope a series of upgrade/equip/development trees, but I hit a rather noobish wall I suppose.

I will paste the exact trigger when I get home, but for now:
C - Unit begins to cast ability
A - If :
Ability being cast = (ability1)
Then:
do ____

When I test it, and click the ability, the game crashes and I get an error message.
The ability itself was... shit... I forget, but I selected a skill and removed it's stats, so all you can do is click it, and nothign will happen.
I think I did somethign to the skill to make the game crash.

So what it comes down to is, I think, what's a good way to make a dud-skill that does nothing, but a trigger can recognize that it is being cast?

Thanks.

Try basing the ability of off other abilities. Some good dummy abillities are thunder clap, frost armor(non auto-cast), evasion and tranquility.