Bomy pet help!

[fireball_dolphonia]

tell me whats wrong with that part
;
with (getplayer(#s(this.followperson))) {
noowner = false;
if (!strequals(#F,#L)) {
// Player leaved the level, so follow him
setarray this.followpos,0;
dir = playerdir;
warpto #F,playerx,playery;
}
else {
//
// Follow the player
//
px = playerx;
py = playery;
}
// Add one step to the list if the player has moved
alen = arraylen(this.followpos);
if (alen<2 || this.followpos[alen-2]!=px || this.followpos[alen-1]!=py)
{
setarray this.followpos,alen+2;
this.followpos[alen] = px;
this.followpos[alen+1] = py;
}
// Only save 4 steps, so delete one entry at the beginning
// if there are too many
if (arraylen(this.followpos)>4*2) {
for (i=0; i<4;