ASPNETVideo and literals - getting information from database into form and run a video

 Hi all,
I have a problem that I have tried to solve for a while. I want to show video on a .aspx page so that the video filename is taken from a database.
I have used literal to define the film:
Dim film_id As String = DetailsView1.DataItem("FILE_name")
ltlFilm.Text = "<ASPNetVideo:WindowsMedia ID='WindowsMedia1' runat='server' VideoURL='http://www.video.com/film/"
ltlFilm.Text &= film_id & ".avi'> </ASPNetVideo:WindowsMedia>"
This is then shown on the web page by this code:  
<asp:Literal ID="ltlFilm" runat="server"></asp:Literal> When I view the page there are no error messages but the film is not shown in the page either.
Now if I copy the code from the browsers "View Page Source" and paste it into .aspx page and view that with a browser - the film is shown perfectly. So ...