Hi Ronny,
Two answer both of your past questions:
In regards to the character encoding, if you are using the Adobe LiveCycle Barcode Forms ST 7.0 Decoder then do not touch the encoding method on your form. Leave everything in the default configuration and it should work out of the box.
In regards to the forms filled out with Reader 8.x, the decoder is not really meant to decode "saved" forms. The PDFs and TIFs that are supposed to be decoded are those of scanned forms that have been printed and then scanned. The workflow really needs to be: download form, fill-in form, print form, return form, scan form, decode scanned image.