Challenge error: Data can not be updated into ODS.

Hi,gurus.

I can not update data from ZODSA to ZODSB by DTP. DTP extraction mode is Full. No any delete code in the start routine.No filter conditions in DTP.

The DTP detail:

Extract. from datastore xxxx : 50000 data records

Filter Out New Records with the Same Key :50000 -> 50000 Data Records

ODSO ZODSA -> ZODSB : 50000 - > 755 Data Records

Update to DataStore Object ZODSB : 755 -> 0 Data Records

Why can't the 755 records be uploaded into ZODSB?

What's wrong?

BTW: In first time,ZODSB can get data from ZODSA,but when I delete the content of ZODSB and run DTP again,ZODSB can not get any data from ZODSA.But we do nothing about ZODSA and ZODSB.