I used to have the problem that my big boy Taz-man would not use the
litterboxes, they are all over the house.  I locked him in a cage until he
would go but he wouldn't go in the box.  I then found a box in walmart that
works, I found out he was too big to fit properly in the box.  He like to
get all the way in the box to go.  I bought these wallpaper trays in the
paint section they look like the long 3ft patio flower boxes, but they are
a thin white plastic ane he loves them.  They all poop in the corner and
the center is free of poop so they can get in and out w/o getting poop on
them.
 
Try this .  It worked for my guys.
Rocky
[Posted in FML issue 2682]