I am having problems when I am using the 3D graphics of the Nokia 6131 and 6131 NFC.

When I am loading a image from a PNG or a GIF with Image.createImage("/myFile.png") and I put it directly to the screen, the device shows the image well with the transparency information, but when I put the image in a Sprite3D or I create my own texture, the device does not draw the image respecting the transparency information.

Is that because the file format? Is there any trick that I forgot to use? In 2D, no problem, but I have not got to do it in the 3D space.