Hi Bighnajit,
Two possible reasons why the SD bill didn't get picked up in the batch.
(a) It may happen that the SD bill has been posted in SAP after the invoicing batch job has already run in SAP for the day. Check the creation of the SD bill in SAP.
(b) Ideally, SD bill should get picked during the EA26 run while creating the IS-U invoices.
Check the parameters for EA26-General Selections,Custom Selections if there is something maintained which is not allowing to pick the SD billing in the EA26 batch job.
Hope it helps...
Thanks,
Amlan