I already tried some combinations:

1 - Design to NONE, in the end of the code changed to FILL, columns doesn't adapt at all...
2 - Design to FILL, before adding the column set to NONE, after finishing set to FILL, the columns in the datatable fill the space but the new column doesn't... scrollbar visible.
3 - Design to FILL, before adding the column set to NONE, in the column changed the AutoSizeMode to fill, when the code reaches the addding part it jumps out...

By adding the columns to the datatable directly, should work.

But sometimes by some reason the columns must be added directly to the datagridview without messing with the datatable... and in those situations why we can't add columns when set the auto size columns mode to fill.
Some kind of issue with this combination? Datatable + Fill + Add Column?

Thanks