Unable to update Confirmed quantity automatically from Webservice call in Schedulling agreement

Hi All,

We are making a webservice call from external system and  inside SAP the FM SD_SALESDOCUMENT_CHANGE is called. When same FM is called form idoc its updating order quantity and confirmed quantity in schedule lines. where as if i call with same data and same FM it only updates order quantity but not confirmed quantity.

 

can you please suggest here.

 

Regards

Mamata