When I try to test the extracter RSA3 in ECC it tells me No data selected. There was not down at any poit of time.
In RSA3 you need to provide any leading zeros to test. If not, the extractor check wont return any records, For ex - the doc number is of length 10, so if your document number is of 9 length you have to add a leading zero.
What could be possibly be the issue? - many things like - parked documents are not picked by the GL extractor
how can I move this dropped part of data to BW system? - do a full load for the missing documents