Dinesh,
Take One PO and verify how many Line items exists in DSO, RSA3 and PSA.
1. Compare the records btw RSA3 and PSA, if it matches then proceed to next step if not verify how many requests are there in PSA..
2. Compare PSA Vs DSO check number of records, If record count doesnt match then compare Keyfields with EKPO with Your DSO table and adjust accordingly.
Thanks,
SB.