Could not able to Generate next Lot Serial Nbr

I have did a customization where using the pre assigned lot serial nbr feature to show the next lot serial nbr. i have did using the below code

 PXResult<InventoryItem, INLotSerClass> result = new PXResult<InventoryItem, INLotSerClass>(invitm.Current, iNLotSerClass);
                                    ILotSerNumVal numVal = INLotSerialNbrAttribute.ReadLotSerNumVal(this, result);
                                    numVal.LotSerNumVal = numVal.LotSerNumVal + iNLotSerClass.AutoNextNbr;
                                    string autoincrementnbr   = INLotSerialNbrAttribute.GetNextNumber(invsetting.Cache, iNLotSerClass, numVal);
                                    // invsetting.Current.LotSerNumVal = INLotSerialNbrAttribute.GetNextNumber(invsetting.Cache, iNLotSerClass, numVal);

Where it was working fine in 21R1 but when i check these in the 22R1 its not generating the next lot serial nbr  using INLotSerialNbrAttribute.GetNextNumber(invsetting.Cache, iNLotSerClass, numVal);
all the time the lotserialnbr = LREX0000