Creatures Caves

At the moment, I'm working on coding the Zanderfish for the Past Seas metaroom. For the most part, they work right.

Their timer script:

scrp 2 15 18870 9
doif carr = null

*Room Checker
doif rtyp room ownr <> 8 and rtyp room ownr <> 9
accg 3
loop
doif obst down <= 1
setv velx rand -2 2
setv vely -2
doif velx < 0
anim [0 1 2 3 4 5 6 7 255]
else
anim [8 9 10 11 12 13 14 15 255]
endi
endi
addv ov99 1
untl rtyp room ownr = 8 or rtyp room ownr = 9 or ov99 >= 50
doif ov99 >= 50
gsub dead
else
accg 0
setv ov99 0
endi
else
*Age a bit
addv ov01 1

*Grow up if old enough
doif ov01 >= 50 and ov00 = 0
gsub grow
elif ov01 >= 150 and ov00 = 1
*Kick the bucket due to old age
gsub dead
endi

*Check for overpopulation
doif rand 0 2 = 1
setv va00 0
esee 2 15 18870
addv va00 1
next
esee 2 18 18870
addv va00 1
next
*If over 20, kick the bucket
doif va00 > 20
gsub dead
endi
endi

*Time for reproduction
doif ov00 = 1 and rand 0 1 = 1
gsub repr
endi

*Random movement
gsub rndm
endi
endi

*Subroutines start here

*Dying
subr dead
lock
velo 0 0
*First, stop moving
doif ov10 = 0
pose 0
else
pose 8
endi
*Then, sink to the bottom
accg 0.5
loop
wait 5
untl obst down < 5
*Wait some more, then rot
wait 100
*If an adult, produce fishbones
doif ov00 = 1
doif ov10 = 0
setv va03 32
else
setv va03 33
endi
setv va00 posl
setv va01 post
setv va02 plne
inst
new: simp 2 10 18870 "ps_zander" 1 va03 va02
attr 194
bhvr 48
accg 3
aero 0
perm 30
elas 0
fric 70
tick rand 200 400
targ ownr
kill ownr
*If not an adult, then just rot here
else
doif room ownr <> -1
altr room ownr 4 0.01
endi
kill ownr
endi
retn

*Growing
subr grow
*First, stop moving
velo 0 0
*First, make sure you're not too close to a wall
doif obst left > 50 and obst rght > 50 and obst down > 50 and obst _up_ > 50
*Then, change bases and change lifestage. That's it.
doif ov10 < 0
pose 0
else
pose 8
endi
base 16
setv ov00 1
else
*Otherwise, do this fancy shmancy routine that should help prevent invalid position errors
setv va00 posl
setv va01 post
setv va02 attr
attr 0
doif ov10 < 0
pose 0
else
pose 8
endi
base 16
mvsf va00 va01
attr va02
setv ov00 1
endi
retn

*Reproduction
subr repr
setv va00 0
*Count surrounding fish/eggs
esee 2 15 18870
addv va00 1
next
esee 2 15 18870
addv va00 1
next
*If too few, lay eggs
doif va00 <= 6
setv va01 posx
setv va02 posy
inst
reps 3
new: simp 2 18 18870 "ps_zander" 1 34 500
attr 194
bhvr 48
accg 0
aero 10
perm 30
elas 0
fric 50
tick 1
*ov01 = grow counter
setv ov01 0
mvsf va01 va02
addv va01 4
repe
endi
retn

*Random Movement
subr rndm
*First, an obstacle checker
doif obst left < 50
setv ov10 rand 2 3
elif obst rght < 50
setv ov10 rand -2 -3
else
*If not close to a wall, then loop until ov10 <> 0
loop
setv ov10 rand 3 -3
untl ov10 <> 0
endi
doif obst down < 50
setv ov11 rand -1 -2
elif obst _up_ < 50
setv ov11 rand 1 2
else
setv ov11 rand 2 -2
endi
*If ov10 < 0, animate left, otherwise animate right
doif ov10 < 0
anim [0 1 2 3 4 5 6 7 255]
else
anim [8 9 10 11 12 13 14 15 255]
endi
velo ov10 ov11
retn
endm

For some strange reason, however, when they try to reproduce they throw this error:

Error Message wrote:
Runtime error in agent 2 15 18870 script 2 15 18870 9 unique id 1029547
Anim change failed - on part 0 which has base 0
... endi doif ov10 < 0 {@}anim [0 1 2 3 4 5 6 7 255] els ...

When the bit that tells them to reproduce is commented out, this error does not occur - however, this also leads to another bug: The adults, when they die, don't leave a skeleton behind like they should.

I cannot figure out solutions to either of these problems - the script looks like it should work, but it doesn't. At least not correctly. Can anyone else find out why?