If UAC is enabled, you cannot bypass the UAC prompt, and this is by design. See FAQ: Why can't I get around the UAC prompt? for more information. Excerpts:
If you could mark the application to run with silent privilege privileges, what will happen to all of these applications with LUA errors there? Answer: they will all be marked to quietly pick up. How will future Windows software be written? Answer: To quietly raise. No one will actually fix their applications, and the end-user applications will still require and work with full administrative permissions without the need.