AX 2012 reserve Purch

public void reserve_Purch(PurchId _purchId)
{
    PurchLine               locPurchline;
    PurchLine               ReserverPurchline;
    InventMovement          inventmovement;
    InventUpd_Reservation   reservation;

    inventdim   inventDim,iDimNew;

    locPurchline = PurchLine::find(_purchId);

    ReserverPurchline = PurchLine::find(HachuTable.Z_PurchId);

    inventDim                = ReserverPurchline.inventDim();

  
    inventdim.InventLocationId = copy_Table.Z_InventLocationId;
    inventdim.inventBatchId = copy_Table.Z_InventBatchId;

    iDimNew                  = inventDim::findOrCreate(inventDim);
    inventMovement = InventMovement::constructNoThrow(locPurchline,InventMovSubType::None);
    reservation = InventUpd_Reservation::newinventdim(inventMovement,iDimNew,copy_Table.Z_ReturnQty, false);
    reservation.updateNow();

}