Problems with Transparency

[Karnizero]

Im having trouble to get the textures with transparency to work.

I have created a texture, in PNG format. I'm using a PK3 file instead a WAD, so there is no software changing the PNG image.
All seems correct, and The Gimp shows the transparency correc, but when in game:

-> If i set the image background transparent, the texture is not shown
-> If the image background is black, the texture is shown, but the black scale is not interpretated as transparency scale, so the game shows the black scale as a normal color.

Im trying this with 1.30, and i think i'm missing something, because other maps with similar textures are shown correctly...
Even when i use those map's transparent textures on my map, i got the same problem as when using my texture, so i think the problem should be in the map.

[EDIT]

I tested the map on GzDoom, and work fine.
What could be the problem, then?

[Janis Legzdinsh]

Try to enable "blend sprite borders" option.

[Karnizero]

Try to enable "blend sprite borders" option.

It works. That was the problem. Thanks.