BACK_CALCULATION_ERROR:
QP_PREQ_PUB.BACK_CAL: NO MANUAL ADJ error after you tried to override the price defaulted from Price List.
Fix => Define Discount Modifier, set it to Manual, Modifier Type = Discount, Override flag = Yes. Assign it to the right Qualifier.
Fix => Define Discount Modifier, set it to Manual, Modifier Type = Discount, Override flag = Yes. Assign it to the right Qualifier.