Control on Advanced Insert dialog does not show in Internet Explorer 10

[Oneview Corp]

Hi,

We have a custom drop down box in the AdvancedInsert dialog that lists the services someone can select from. It works in Chrome, Firefox and IE 11 on Windows 8. But it does not show up in Internet Explorer 10 or 11 on Windows 7. Only the first line of text from the combo box shows up and no down arrow that indicates that it is a combo box.

                 RadComboBox appointmentType = new RadComboBox();

                    appointmentType.Items.Add(new RadComboBoxItem("1. Existing Client: (15 min)"));
                    appointmentType.Items[1].Value = "15";
                    appointmentType.Items.Add(new RadComboBoxItem("3. New Client: (60 min)"));
                    appointmentType.Items[3].Value = "60";

                subject.Parent.Controls.Add(appointmentType);

                appointmentType.Label = "Service ";
                appointmentType.Width = Unit.Percentage(90);
                appointmentType.Style.Add("position", "absolute");
                appointmentType.Style.Add("top", "40px");
                appointmentType.Style.Add("left", "30px");
                //appointmentType.Style.Add("z-index", "0");​

Could you please help us resolve this?

thanks