asp.net how to access route data from an iframe

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ASP.NET

I have a basic asp.net page with an image upload loaded through an iframe:

<asp:Panel runat="server">
      <asp:TextBox runat="server" id="imgCaption" CssClass="imgCaption" PlaceHolder="caption(optional)" />

      <asp:FileUpload runat="server" ID="programmImages" Width="200px" CssClass="offScreen" />

      <asp:Button runat="server" id="hiddenImageUpload" OnClick="UploadImage" CssClass="insButton" Text="Upload" />
 </asp:Panel>

the image upload depends on the route data in order to upload but whenever i try to upload the image i get this error:

> Object reference not set to an instance of an object

on this line:

var ProgName = Page.RouteData.Values["prog"].ToString()

;

this line works fine in other pages.

so how can i retrieve the route data through the iframe.

Thanks