popping up download dialog box

Hi every body ! I am writing a script which pops up download dialog box on click of a Link. Headers i m sending out for downloading jpegs are: header("Cache-control: private"); header("Content-Type: image/jpeg"); header("Content-Type: application/octet-stream"); header("Content-Length: $size"); header("Content-Disposition: attachment; filename=$fname"); header("Content-Transfer-Encoding: binary"); readfile($fname); All these work well in MSIE 5.0+ and Netscape 4.7+ . But on Mac I.E its not popping up the dialog box rather it opens up the jpg file in the browser window. I don know where am i doing wrong. Please suggest me . I cracked my mind for hours but in vain. So please help me out. Thanks in advance Binay