How to get the Total Amount and the Tax fields in Purchase Order Adobe Form

Dear Expert,

I have an issue for to calculate the Total Amount and the Tax fields in my Purchase Order. This is a copy of MEDRUCK_PO and my printer program is a copy of SAPFM06P .

I tried with multiples codes in javascript in my adobe form to solve this issue but i didn`t have success...With routine in adobe form too...

In the Printer Program, the table that contains this data to fill the Form is IT_KOMVD . The field in this table is KWERT. ¿Is it correct?

This bring "Tax", "Total Amount" and "Net ..." And I only need the Tax and Total Amount

How could I get this data to my Adobe form?

Thanks for all.