When I tried to change the material in a PO using BAPI_PO_CHANGE, I am getting error "Change material could not be effected", even though the GR not happened for that. But manually I am able to change it in ME22N Tcode. I have passed the following parameters;
1) PO number
2) PO line item
3) Material number
and corresponding entries in POITEMX also.
Please provide the solution. Reward points for the helpful answer.