Hi Tobias,
The dates to be billed are with the status A . I have entered the billing date for the contract from 1.08.2013 to31.08.2013. Alternatively i have also tried with contract number only,
Upon changing the date for 31/08 to 30/08 saved and tried vf04 it was working. I came back and changed the billing date to 31 /08. well it worked.
I believe this was maybe due to the fact that date table was not getting updated, as we had migrated to new hardware in august.
Thanks
Regards