Whenever I try to run a page with a stylesheet link in it, I get an error that says you need runat="server" in the head tag.

So I found this and tried it in the Page_Load event

Code:
        HtmlLink fred = new HtmlLink();
        fred.Href = "Stylesheet.css";
        fred.Attributes.Add("rel", "stylesheet");
        fred.Attributes.Add("type", "text/css");
        Page.Header.Controls.Add(fred);
But when I run it it says

Object reference not set to an instance of an object.

Why? When I am typing it intellisense fills it all in. I have used the 'new' keyword. What is wrong?

Thanks for any help.