Call to undefined function

I checked one after another modules inside xml.

I got this error:
warning: array_merge() [function.array-merge]: Argument #2 is not an array in /home/autismoa/public_html/sites/all/modules/xmlsitemap/xmlsitemap_term/xmlsitemap_term.module on line 189.

while trying to turn on the "xml sitemap file".

If I unchecked it works properly and does not show the "fatal error: Call to undefined..."

Since I have my files protected, I wonder if this issue has anything to do with it.
I guess that the above warning would be ok, but to destroy the xml file seem excessive.