Hello Sunanth,
Error QHU006 has been related to the customising of movement type 321.
Check view V_TQHU1 for type 321.
If the indicators 'usage decision made' (V_TQHU1-VEREC) and 'UD with accepted' (V_TQHU1-VEACC) is set a usage decision has to be done before doing stock postings outside the usage-decision. Also, the usage decision has to be accepted and the quality has to be greater than the 'Q-score greater'.
I do not know how the user could save the UD, but the right thing to do would be record the usage decision with an accepted usage decision code and with a q-score greater than that maintained. Stock posting in usage decision needs NOT be done. Then it should also be possible to do the stock posting in the delivery.
Regards,
Natália