ERROR IN BAPI BAPI_ALM_ORDER_MAINTAIN

Hi,

I used BAPI BAPI_ALM_ORDER_MAINTAIN to change operation of production order but I unable to make changes due to error of purchase requisition and error number is 184. I just share screen shot of error which come while I want to change operation control key.

please suggest me if anyone has solution of this particular problem/error.

thanks in advance.