Scheduling agreement changing terms of Payment

Hi.

I am implementing a little custom program, which have purchaging Doc, vendor, a checkbox to use or not the Standard Text, and a text box.

It will change the Terms of Payment (Long Text) with the Standard Text if the checkbox is checked or with the manual text in the textbox.
After some checks, I save the Terms of Payment with this,

concatenate gv_ekko-ebeln ” into ls_name.
lwa_header-tdobject = ‘EKKO’.
lwa_header-tdname = ls_name.
lwa_header-tdid = ‘L07’.
lwa_header-tdspras = ‘S’.

call function ‘SAVE_TEXT’
exporting
client = sy-mandt
header = lwa_header
savemode_direct = ‘X’
tables
lines = ls_lines
exceptions
id = 1
language = 2
name = 3
object = 4
others = 5.

But after consulting the document i saw the terms of Payment is empty (see image)

Any ideas to change the terms of payment?

Thanks in advance