Feedburnere sitemi ekleyince böyle bir hata alıyorum. Nedeni nedir acaba

The URL does not appear to reference a valid XML file. We encountered the following problem: Your feed has an invalid character(s) in it. This may be caused by editing your posts with a wordprocessing program. Try copying your posts into a plain text editor (like Notepad or TextEdit) before pasting them in your blogging tool.