Adding Dynamic Control to Master Page from Masterpage

Hello forum, 
I seem to be having problems with something that I thought would be simple
I have 

Private Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender Dim metaDescLiteral As New Literal metaDescLiteral.Text = "<meta NAME=""DESCRIPTION"" CONTENT=""grhaman"">" metaDescLiteral.ID = "graham" Page.Header.Controls.Add(metaDescLiteral)end sub
and I get the error "object not set to an instance of an object" - I have moved it from prerender to load and tryed all sorts of things, but I get the same error.
I am just trying to add a literal control to the masterpage from the masterpage code behind







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