Enter Net Price Error in SRM System

Dear Gurus,

The user has created Purchase order in SRM Portal without flagging 'Confirmation-Related Invoice Verification' and 'Invoice Expected'. The PO is transferred to R/3 system with '0' price and free goods indicator. Then the user modified the PO in the portal, flagging the Confirmation-Related Invoice Verification & Invoice Expected indicator.

Now the changes is not getting transferred to R/3 and getting error message as 'Enter Net Price' in RZ20.

Is there any note on this issue.

Please throw some light to resolve this issue.

Regards,

Suresh