Wizard Control not posting back in IE

I'm trying to setup a 2-step wizard control, but in Internet Explorer it is not posting back on clicking the next button. Other browsers are fine... this is just an IE issue. In IE nothing happens when I use the 'next' button to try to proceed to the 2nd step.... no errors... nothing.
My code:
<asp:Wizard ID="wzOrderForm" Width="100%" DisplaySideBar="false" DisplayCancelButton="false" StartNextButtonText="<%$ Resources:wsGeneral, langStepNext %>" FinishPreviousButtonText="<%$ Resources:wsGeneral, langStepPrevious %>" FinishCompleteButtonText="<%$ Resources:wsPluginCWWintern, langActionPlaceOrder %>" runat="server"> <WizardSteps> <asp:WizardStep ID="WizardStep1" runat="server" Title="Step 1"> <h2> <asp:Literal Text="<%$ Resources:wsGeneral, langStep1Of2 %>" runat="server ...