I am facing a problem with an installation of your script. I installed the sitemap.xml script on an OpenCart website ([external links are visible to admins only]) and after crawling, the sitemap.xml seems to be empty. You can see it here: [external links are visible to admins only]
I realized that, when I added that on Google Webmaster Tools and it returned the error that sitemap.xml is empty.
The strange is that when you download the file and open it with notepad++ has thousands of lines!
Could you please advise?
Finally, please let me know... I have purchased version 6.0. Do I have the right to get ver.7.0 or should I buy it again?