transparency

hello everyone, I have asked this question some time ago in the vidvox forum. I might go into some details at explaining my problem again. I have an image of some birds sitting on a power line. I cut out the birds and saved them as a png file with a transparent background. I want to overlay them to original image. the final composition for vdmx should be able to zoom in to the "cut out-picture. thus, the birds will change size, while the rest of the picture remains just a still. the problem is quite simple: I want to overlay a png or psd file wit a transparent background. I have tried to change the blending of the sprite to OVER. and it doesn't work. Someone has sent me his qtz-file, which worked fine on his laptop, but not on mine. I don't understand why this happens. The only difference was the version of QC. On his system, her was running some older version. I am running QC 4 with snow leopard. Are there known issues with QC4 and snow leopard? Is there some way to go back to QC 3 (but keep snow leopard)? has anyone suggestions for how to solve this problem? best, moorooduc