<telerik:RadComboBox ID="rdVacantBu" Skin="Web20Ext" CheckBoxes="true"

CheckedItemsTexts="DisplayAllInInput" EnableCheckAllItemsCheckBox="true" EmptyMessage="Please Select" ForeColor="Black"

Localization-CheckAllString="All" Visible="false" Font-Italic="false" EnableEmbeddedSkins="false"

BackColor="White" runat="server"> </telerik:RadComboBox>

ShowWindow()
{
var omanager = GetRadWindowManager();
var ownd = omanager.getWindowByName("DialogWindow1");
ownd.show();
}
 

<asp:ScriptManager ID="ScriptManager1" runat="server">

</asp:ScriptManager>

<telerik:RadWindowManager id="Singleton" runat="server" ClientCallBackFunction="ResetPasswordWindowClosed" >

<windows>

<telerik:RadWindow id="DialogWindow1"

Modal = "true"

Runat="server"

Width="600px"

Height="250px"

Title="Reset Password"

NavigateUrl="~/Support/ResetPassword.aspx"

Skin="WebBlue"

VisibleStatusbar="false"

Behavior="Close"

>

</telerik:RadWindow>

</windows>

</telerik:RadWindowManager>


//and in code behind

public void OpenResetPasswordWindow()
{
literalInjectJavascript.Text = "<script type='text/javascript'> ShowWindow(); </script>";
}

I've tried numerous different examples from telerik site but whenever I call GetRadWindowManager() the result is always 'undefined'.

Your help is most appreciated as I've spent most of the day trying to get this working.
Thankyou