Vendor Invoices - Entered on and parked details not correct

Hi since we upgraded to ECC6 we have noticed that the dates stored in the Header of both LIV and Direct Entry invoices are not correct.

If we Park a invoice we have a the corrected Entered on and Entered By details is correct.

Then when the document is posted the entered on date and user name then changes to the date the invoice was posted on the system.

We need to be able to see when the document was originally put on the system as a parked document so we can determine how long it takes us to process them.

I have checked in bkpf and usname and ppnam is the same and nothing in sname.

I cant see any OSS notes to say this is a known problem. Does anyone know how to resolve this.

Thanks