"Object reference not set to an instance of an object"

I'm trying to write a script to post large numbers of image links to a page. 
The codebehind looks about like this

for (int i = 0; i < 200; i++)
{
     HyperLink link = new HyperLink();
     Panel1.Controls.Add(link);
}
and the HTML is
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
    <asp:Panel ID="Panel1" runat="server">
    </asp:Panel>
</asp:Content>


the problem is, I did a site back a while ago and had the same problem.  For some reason it stopped happening and I never had any idea why.  When I copied the code over to this project, it stopped working.  I know this is one of the most common errors but I cant find anything that replicates this situation.  Most articles say I need to ...