Small assembly program

I would like to use UV2 to Debug the following assembly language program on a Phytec C508 target board using the Keil Monitor-51 driver.

org 0000h
main: mov R0, #00h
mov p1, #0ffh
mov p2, #0ffh
end

However, when I Debug and single step into the program the code is not executed. When I Run, the code is not executed.

Are there settings in UV2 that need to be set?

Is there a minimum amount of additional code that needs to be added to test this simple assembly program?

Thanks