Do not use proxy fields in this case : the proxy field has a differnt name from the proxied field, and it's not yet supported (prevents frm saving the value contained in the field).

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@8354 20353a03-c40f-0410-a6d1-a30d3c3de9de