Not working in extra Textarea

Hi,
im using Siemple Field plugin (http://ww.wp.xz.cn/plugins/simple-fields/) to add extra field in the content type.
Im adding some extra Textarea, but is not working in this one!
Is there a way? Thanks a lot and really good job

Thanks
Matteo

http://ww.wp.xz.cn/plugins/preserved-html-editor-markup/