I should add that the script works in a CGI environment, i.e Zope behind Apache, with the cgi-bin exposed. Could the problem be something to do with the external method attempting to write a png on the fly? Harlow Pinson Indepth Learning Email: hpinson@indepthl.com Web: http://www.indepthl.com Voice: 505-994-2135 FAX: 208-475-7678