cannot import images

[fgj2wp] Can’t copy /pat/to/image.gif to /home/ieffect/domains/domain.com/public_html/testwp/wp-content/uploads/2006/07/image.gif : De opgegeven URL is ongeldig. (that’s Dutch for: the URL is invalid)

http://ww.wp.xz.cn/plugins/fg-joomla-to-wordpress/