Hi,
It seems you have posted the remaining amoung amount as the tax amount . For 17400 if the tax is 538 then fine . There will be no issue . Post a subsequent debit document for the amount 538 . This sets the PO history .
If not the tax amount posted in earlier invoice is not the correct one , calculate the correct tax amount for the full amount and bifurcate the remaining amount in the subsequent document .
Hope this sets .
Regards,