This problem is in the category of "bad things that happen when
generated xml" [aka A Bug]. Most of the answers I found invovled
checking particular settings, which could be the cause, but in my case
all of the settings were fine, but the problem still persisted. I
resolved mine by deselecting the "Include Header.." checkboxes, then
changing the row from Header Row to Body Row, then back to Header Row,
then selecting the "Include Header..." checkboxes. Voila!Hope this
helps.