Using vertex coloring to make a unit transparent

Having some problem with the following code. I've added debug messages to confirm that everything is working and that the target unit of ability being cast is set (I tried performing another action on the unit which worked fine).
The color settings are working, it's just the transparency that isn't.
The annoying thing is that I did have transparency working in this way on another map that I have since deleted.
I'm stumped as to why this isn't working...

I dont think it works with Channeling event...
Try to use starts the effekt.

But the following trigger works perfectly, so it can't be that.

20% isn't likely to be easy to notice. Try 100%.

hmm I am no expert but it has to be something. My guess is the conditions arent satisied. I suggest u start by checking if vertex colouring works with ability channeling. If it does, then that means its likely the conditions arent satisfied.

Could it be because u are using the same variable for 2 abilities?

I figured it out. The above triggers don't actually include some actions that I thought were completely inconsequential. One of these ultimately led to corrupting the variable in another trigger. D'oh!