SiteSucker is a relatively simple program and it has a number of limitations.
SiteSucker only examines CSS and HTML for URLs. When SiteSucker analyzes HTML, it looks for URLs in the style attribute and in the following tags:
If a link is specified elsewhere in an HTML file, SiteSucker will not see it.
By default, any directories or files disallowed by robot exclusions will not be downloaded by SiteSucker. See Robot Exclusions for more information.