We are facing issue in FB50 substitution for functional area. We have created a substitution and given prerequisite as BSEG-HKONT and set created for GL accounts list. If FB50 GL available in the set then it should substitute FA which we have given as constant value. It is working for all transactions. But only in FB50 we are facing issues. In FB50 also if we fill one line item completely and come to second line item and fill, the FA is updating correctly. Only the problem is when we fill all the line items in FB50 at a time, the FA is not getting updated. It sounds very strange. We checked by tracing also, the trace also worked only if we enter one line completely and going to second. If we give all line items at a time, the trace didn't worked. Please help.