The Dink Network

I know I already asked this a while ago, but I still can't seem to get it to work. Here's a piece of the script:

void main( void )
{
sp_brain(&current_sprite, 9);
sp_speed(&current_sprite, 1);
sp_exp(&current_sprite, 3);
sp_base_walk(&current_sprite, 850);
sp_touch_damage(&current_sprite, 2);
sp_hitpoints(&current_sprite, 6);
preload_seq(851);
preload_seq(852);
preload_seq(853);
preload_seq(854);
preload_seq(855);
preload_seq(856);
preload_seq(857);
preload_seq(858);
preload_seq(859);
sp_follow(&current_sprite, 1);
sp_target(&current_sprite, 1);
set_smooth_follow(&current_sprite, 1);
}

The problem is, the sprite won't walk in all 9 directions. When trying to walk diagonally, it just moves vertical and horizontal very quickly. According to the DinkC Reference, set_smooth_follow should enable the sprite to follow Dink in all 9 directions, so there must be a way...