Seo Ad On Not Working

The SEO friendly url is not working on my site, at the minute it is disabled and when i try to enable the SEO add on i get the error message

SEO-friendly URLs are disabled. Check your web server and URL manipulation engine settings.

I have spoken to my host who is telling me that the problem is due to an error in the php code for the add on.

My host has checked the .htaccess file and all is ok there so i then followed the advice on this forum to go to Public_html/addons/seo/schemas/settings and add the return true; but this still has not solved the problem.

Has anybody found a solution for v3?