Change material could not be effected - Error in BAPI_PO_CHANGE

Dear all,

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.

regards,

Chandra.