WebCombo losing icon, after first drop down, if its displayed inside iframe.

Any solution to that.

<iswebcombo:WebCombo ID="cmb1" runat="server" UseDefaultStyle="true"  Width="250px" DataTextField="Field1" DataValueField="Field2" AllowWildCardSearch="true" >
                            <LayoutSettings ComboMode="MultipleColumns" AlwaysShowAllRowsOnDropdown="true">
                            </LayoutSettings>
                            
                            <Columns>
                                <iswebcombo:WebComboColumn Bound="true" BaseFieldName="Field1" Name="Naziv" HeaderText="Field1" Width="350px" />
                            </Columns>
                        </iswebcombo:WebCombo>