Hi,
fck-editor will only be shown in the real reply-form, the fast-reply-form at the bottom of the topic will use xoopsdhtml. Your configuration of the forum seems ok. Did you already install fck-editor from here? If not download it here
http://xoops.peak.ne.jp/md/mydownloads/singlefile.php?lid=93&cid=3 and just upload it to your webspace. Only this fck-editor made by Gijoe will work with d3forum and his other modules like pico.