Liquid Fire

I'm trying to make a hero version of Liquid Fire, now. I think I've got everything set correctly, but it's not coming into effect. At the moment, the only thing changed from the normal Liquid Fire is that it's a hero spell and it targets units instead of buildings. So why doesn't it work?

Did you remove the upgrade required? I tried it and it worked fine.

Yeah, I did. That didn't fix it, but changing the units attacked to ranged did.