Hi Arun,
I think you have to manually populate the amount, fkkopk-betrh and fkkopk-betrw, which is coming in the T_FKKOPK structure.
Also I think you need to manually populate the amount subjected to tax in local currency, fkkopk-sbash and amount subjected to tax in transaction currency, fkkopk-sbasw as well.
Once you have done that, then modify the T_FKKOPK structure and then copy them to T_FKKOPK_NEW structure
I think it should be fine after the above.
Hope it helps..
Thanks,
Amlan