ComboBox.SelectedValue is not Working

This does not answer the OP however...the ComboBox SelectedValue must be an integer type.

If you have a short or byte var that holds the value that will set the SelectedValue, it won't work - you will have null/nothing value.

Use an integer.

Both ValueMember and DisplayMember properties are used only if DataSource property is defined.

So, you should re-write your code as follows:

private readonly BindingList<KeyValuePair<string, int>> m_items =
    new BindingList<KeyValuePair<string, int>>();

public YourForm()
{
    InitializeComponent();

    cboGridSize.DisplayMember = "Key";
    cboGridSize.ValueMember = "Value";
    cboGridSize.DataSource = m_items;

    for (int i = 2; i <= 12; i++)
        m_items.Add(new KeyValuePair<string,int>(i.ToString(), i));

    cboGridSize.SelectedValue = 4;
}

Links:

• BindingList class
• ObservableCollection class
• INotifyCollectionChanged Interface