Light Gun problems with House of the Dead 2

[cods]

The light gun, even after calibration, does not work properly.
It seems to jump around all over the screen, and does not shoot accurately, if on screen at all.
I had the 50hz PAL version of HOTD2, so I patched a 60hz (full screen NTSC) backup, and it has the same problem.
I am using the MadCatz gun. My DC is PAL.
Have not tried using VGA as yet.
Anyone else have similar problems, or a solution?
Rgds.