Here's a complete example with a basic form and `DataGridView` added via the designer:


Setup and bindings:

```cs
private void Form1_Load(object sender, EventArgs e)
{

    var colors = new List<Code>()
    {
        new Code() {Value= "R", Text = "Red"},
        new Code() {Value= "G", Text = "Green"},
        new Code() {Value= "B", Text = "Blue"}
    };

    var users = new List<User>()
    {
        new User() {Name = "Briana", FavoriteColor = "B"},
        new User() {Name = "Grace", FavoriteColor = "G"}
    };

    var colorCol = new DataGridViewComboBoxColumn();
    colorCol.DataSource = colors;
    colorCol.DisplayMember = "Text";
    colorCol.ValueMember = "Value";
    colorCol.DataPropertyName = "FavoriteColor";

    dataGridView1.Columns.Add(colorCol);
    dataGridView1.DataSource = users;

}
```

Some classes:

```cs
public class Code
{
    public string Value { get; set; }
    public string Text { get; set; }
}

public class User
{
    public string Name { get; set; }
    public string FavoriteColor { get; set; }
}
```

I'm trying to bind separate ComboBox cells within a DataGridView to a custom class, and keep getting an error

> DataGridViewComboBoxCell value is not valid

I'm currently assigning the data source for the cell to an `IList<ICustomInterface>` from a Dictionary I've got. Upon setting the data source however, the index for the `ComboBoxCell` isn't set, so it has an invalid value selected.

I'm trying to figure out how to get it to select a real value, e.g. the 0th item within the list it has been given to remove this error, or find another way to solve the problem. Anyone have any suggestions?
