click on checkbox field in ALV GRID

Hello to all,

I have a problem when a user check a checkbox field in ALV GRID. After this, field in output table (itab) for checkbox is not updated to 'X' (marked) when I process it in USER_COMMAND. However, if user select a complete line, this field is marked correctly in itab table.

Anybody know how to do it?

Thunks and regards.