exportimage by using a jit.desktop and jit.matrix

Hi there,

I tried to export images(such as PNG file) of a patch.
So, I used jit.desktop and jit.matrix but I couldn't generate a correct image.

I connected as "[jit.desktop]->[jit.matrix]", and then I send exportimage message to jit.matrix.
Then, dialog box opend, and I saved PNG file.
But, saved PNG image file was perfectly white.

If I connected as "[jit.noise]->[jit.matrix]" and send exportimage message to jit.matrix,
PNG file that is consisted noisy color was generated correctly.

I work on win 64-bit and Max(6.1.6, 64-bit).
If I work on Max5(32-bit), same patch works correctly.
Is this problem depends on bit-number?