I found that megaproxy works for me too, while normal ual.com does not. Curiously I can cut'n'paste the URL as used by Megaproxy and that does not work. While putting the "broken" URL into megaproxy does work.

Despite intuition to the contrary it would seem that the route to ual.com does make a difference to your chances of success. Very strange. I have no doubt that a look at the source for summary.jsp would indicate where the problem is.