PNG transparency

Hi !
I need some informations ^^
I tried to load a PNG image with transparency, but in panda 3D the png image had no transparency !
I just load it like any other GUI, an di tried with a frame_color(0,0,0,100), but its the same, i get a background color instead of a transparency.
How can i do that ?
thanks

try

myNodePath.setTransparency(1)

Thx !
It works ? with gui object ?

yes it work !
Thanks you !