How to import textures with transparency

Hello everyone

I tried to do my colour art with a textrue. I made the texture at photoshop with a blank layer so I would have the transparency. Then I imported in my color pallette as a texture but it is showing white where it was supposed to be transparent.

With the brush tool and the texture brushes I have no problem there. Is just at the paint bucklet and textures that won´t recognize my .TGA transparency

any idea?