Google XML Sitemaps will not write to sitemap.xml

Anyone have any ideas on how to troubleshoot the Google XML Sitemaps plugin to get it to write to the sitemap.xml file? So far, I have tried changing the file permissions to 755 and 777, and deleting the old file and creating a new one but those do not fix the problem.

I thought that maybe it was conflicting with W3 total Cache so I deactivated and deleted it, but still no cigar. It seems like it must be a plugin conflict, but I cannot seem to isolate which one is causing the problem. Any thoughts?