How do I set comboboxcolumn when datagridviews datasource is a datatable

public Form1()
{
    InitializeComponent();

    //disable column autogeneration
    dataGridView1.AutoGenerateColumns = false;
    dataGridView1.AutoSize = true;
    //bind sample data
    dataGridView1.DataSource = CustomBindingSource();

    //create columns manually
    //TextBoxColumn
    DataGridViewTextBoxColumn txt = new DataGridViewTextBoxColumn();
    txt.DataPropertyName = "EmpId";
    txt.Name = "EmpId";
    dataGridView1.Columns.Add (txt);

    //ComboBoxColumn
    DataGridViewComboBoxColumn combo = new DataGridViewComboBoxColumn();
    combo.DataSource = Enum.GetValues(typeof(Sex));
    combo.DataPropertyName = "Sex";
    combo.Name = "Sex";
    dataGridView1.Columns.Add(combo);

    //that's all!
}