wizard: access ImageButton from code behind

 Hello,
I have this wizard:
    <asp:Wizard ID="Wizard1" ..... >        
    <WizardSteps>
            <asp:WizardStep ID="Owe" runat="server">
        ....
            </asp:WizardStep>
        <asp:WizardStep ID="One" runat="server">
        .....
            </asp:WizardStep>
        </WizardSteps>
        <StartNavigationTemplate>
            <asp:ImageButton ID="StartNext ...