It isn't! :laugh: It's a property of the Items collection.
Try:
ComboBox1.Items.Add("4")
ComboBox1.Items.Add("5")
ComboBox1.Items.Add("6")
ComboBox1.Items.Add("7")
ComboBox1.Items.Add("8")
ComboBox1.Items.Add("9")
ComboBox1.Items.Add("10")
ComoBox1.ListIndex = 0