User blog comment:CitizenA/Paint.NET silhouette plugin/@comment-24.184.105.92-20130327060430/@comment-92.9.58.164-20130403103005

In the files it seems your background isn't a uniform colour and the engine may be using the  edge of the black box somehow. The left hand side of the canvas needs a coloured background to differentiate what is the sprite and the what isn't the sprite. The right hand side needs a black sillhouette on a white background as this just softens the edges of the sprite. Having the base image have a black background as it is also causes a lot of problems, because you can't tell the software what black bits are the sprite and what isn't the sprite. I'd suggest finding a version of the sprite that is clearly cut from it's background or another sprite altogether.