Extract annotation from pdf doesn't work


I'm usig Zotero with zotfile extension, Windows 7. I've got strange square lettres in my pdf annotations extracted such as that exemple :

"Les phnomnes de base apparaissent  travers les tmoignages ou les rminiscences qui nous reportent aux ges les plus "

I tried to annotate with Adobe Reader XI and PDF Xchange Viewer and both results are the same...
Have you got an idea about what problem it can be ?
This discussion has been closed.