FDF file missing file specification entry

Using Acrobat 7 we have created a PDF form that is based on a pdf file which is located on a server. All team members have access to this pdf file. After filling out the form the actual data transfer works via sending just fdf data. The fdf file always contained the actual pdf file specification (path and file name)with preceding by /F key.

All this worked perfectly until the first team members upgraded to Adobe Reader version 9. Filling out the form with Adobe reader 9 leads to fdf files which have no file specification information any more. We have updgraded Adobe Acrobat 7 to Acrobat 9 as well because we thought there is just a problem in creating the actual form. However, Acrobat 9 forms behave the same.

Does anybody know, why fdf files generated by filling out forms with Adobe Reader 9 or Acrobat 9 do not include the actual pdf file information anymore?

Many thanks in advance,
Klaus