I have just finish installing the component, it is a great component.
I am not sure does this only happen to me, when ever I enable the Show Section from the configuration, the site url will become [section_name-{number}].html
isn't the path should be something like
[section]/[cat]/[tilte].html

if i disable the section and just show the category
it work perfectly, so is this a bug??
Anyone can help?

I found the bug for this. Line 298 of /components/com_sef/sef_ext.php. There should be a space before the LEFT JOIN statement:

this

should be


That fixed it for me.