Resize Cells of a DataTable

I´m able to resize the widths of ( Nome) , ( rem) and ( adc ) cells in this DataTable, but I´m not able to resize ( pos )and ( qtd) cells, I cant´ find out why.

DataTable(
            columns: [
              DataColumn(
                label: Text("cod"),
                numeric: false,
              ),
              DataColumn(
                label: Text("Nome"),
                numeric: false,
              ),
              DataColumn(
                label: Text("rem"),
                numeric: false,
              ),
              DataColumn(
                label: Text("qtd"),
                numeric: false,
              ),
              DataColumn(
                label: Text("adc"),
                numeric: false,
              ),
            ],
            rows: controller.menuList
                .map(
                  (item) => DataRow(
                    cells: [
                      DataCell(
                        Container(
                          width: 0,
                          child: Text(item.pos),
                        ),
                      ),
                      DataCell(Container(
                        width: 60,
                        child: Text(item.title),
                      )),
                      DataCell(
                        Container(
                          width: 30,
                          child: ButtonTheme(
                            minWidth: 10,
                            child: FlatButton(
                                padding: EdgeInsets.all(2.0),
                                color: Colors.redAccent,
                                onPressed: () {},
                                child: Icon(Icons.remove)),
                          ),
                        ),
                      ),
                      DataCell(
                        Container(
                          width: 20,
                          child: Text(item.qtd),
                        ),
                      ),
                      DataCell(
                        Container(
                          width: 30,
                          child: ButtonTheme(
                            minWidth: 10,
                            child: FlatButton(
                                padding: EdgeInsets.all(2.0),
                                color: Colors.green,
                                onPressed: () {},
                                child: Icon(Icons.add)),
                          ),
                        ),
                      ),
                    ],
                  ),
                )
                .toList(),
          ),
        );
      });

The pattern here is that the both cells that I cant change the width size are a string numeric,any relation?