Update an itab using ALV GRID

Hi,

I have to update an itab using an ALV GRID, having an editable field.

After having modified the editable field, when I give my user command to update the itab I can verify, in debug, that the field has not been changed (also if I press enter before giving the command).

Note:

1. I'm NOT using OO programming but the functions (REUSE_ALV_GRID_DISPLAY...)

2. I took a look for other posts on this argument but I cannot find a solution

Thanks in advance for every help or suggestion.