using variables as FRAME links

I have a main page that calls a sub page (see code below) and in the
controller I just set link1, link2, and link3 to be some hard coded
test pages, but when i view the frames page below all the frames are
empty. If I move the hard code links into the place of link1,2,3 then
it works fine, but i want to use variables as I want the frames to
display different things depentent on user variables. Does this make
sense? Thanks

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 FRAMESET //EN">
<html>

<frameset cols="33%,33%,33%">

   <frame src="<%= @link1 %>">
   <frame src="<%= @link2 %>">
   <frame src="<%= @link3 %>">

   <NOFRAMES>
      <body>Frames Not Supported</body>
   </NOFRAMES>

</frameset>

</html>