please make sure that file permissions are set correctly for output file. Please also check if generator copyright message is unchanged in the sitemap template.
FYI, here's the modification I wish to use:
HTML Site map Generated by <a href="http://www.xml-sitemaps.com" target="_blank">XML Sitemaps</a>
© <a href="http://www.xml-sitemaps.com" target="_blank">XML Sitemaps</a> -
now = new Date
if (theYear < 1900)
All Rights Reserved<br>
I don't suppose you would consider switching to something like this for the sake of convenience?
Also, I don't see anywhere in the documentation where it addresses permissions on the template file. I already have all the other permissions assigned appropriately.