Alphas not showing up in material?

So I made this material so that I could input it in a fire particle I’m creating, but unreal keeps filling out what should be the transparency with either white or the same color as my image. I watched a tutorial to see if I was messing something up, and it said I should use a .tga file, and I tried that and it still didn’t work. I am confused and distressed, please help.

if this texture have alpha channel, use it as opacity mask.

I feel like an idiot. Thank you so much!!