Why do the edges of my custom icons turn black?

[AC Question]

Hey,

I created some custom app icons as my favorite pack didn't include them. The icons are made in PS and saved as .png with transparent edges. However, if I send them to my account via email and then choose them as icons via "edit -> gallery apps -> download", the edges turn black.

Any ideas what I'm doing wrong?

 

[nckre]

Sorry, forgot to mention, that I'm using Nova Launcher