Citation Manager in Word Document lost

Working on a word document with 99 citations from mendeley, importet citations by the plug-in. After a while continued to work with the word file, but mendeley does not detect or refresh the citations any more, despite active field function ("ADDIN EN.REFLIST"). When I insert a new citation, the manager starts with N° 1. Do I have to reenter all the citations again? How can I prevent these things to happen again? Working with the file on Word 2003 and Wortd 2010 adapted for 2003.
Thanks!
Michel Romanens