Cannot draw on mutable image

[Dirk Schumann]

Hi,

I got a problem with drawing on an image created with the
createImage(int width, int height) method. I use MIDP 1.0 and
everything works fine in the emulator. But when running it on my
T-630, I just get a white image with the defined size. It doesn't
matter what I draw on the Graphics-object, my phone just displays a
white rectangle.
The code should be ok, since it works in the emulator. I also used
several examples from the internet - all with the same result.

Any ideas what might be wrong?

Thanks in advance
Dirk