F1 2019 How I change propperly the sponsors of a livery?

F1 2019 The Game (Codemasters)
The matter is that I can't make the background of the image completely transparent, and white gaps appear. I think that I do it well, .dds archive, I do manually the alfa channel, color+alfa... But anyway it doesn't work.
Thank you
 
OK thank you I will try this afternoon, but you mean black background in the layers, in the alfa channel or in both.
Thank you again
 
OK thank you I will try this afternoon, but you mean black background in the layers, in the alfa channel or in both.
Thank you again
 
Top