Word 2007 Endnote X3 error

I am using Word 2007, and EndNote X3. When I insert a citation I get the error message “The requested member of the collection does not exist” and although the reference seems to be inserted correctly in the text, it is not added to the bibliography at the end. I wonder if there is a conflict between Word 2007 “citations” (which I was originally using in this document) and the Endnote software that I just started using a few days ago. If so, is it possible to clear just “citations” formatting in the word document and not all formatting in the document.