MOVING SPRITE HELP!!!

[navidnabijou]

`Set up
constant1 = 2
hide mouse
randomize timer()

`Loading bitmaps and getting images
load bitmap "airplanesprite.bmp", 0
get image 1,0,0,69,71
load bitmap "alienshipsprite.bmp", 0
get image 2,0,0,53,36
load bitmap "bullet.bmp", 0
get image 3,0,0,12,12
cls

`Declare variables [TO DO]
dim spritenum(constant1)
for n = 1 to constant1
   spritenum(n)=n+2
next n
spriteplace = 1
shipx = 0
shipy = 0
alientime = 0
alienships = 0
counter = 1

`Start the game
cls
print "Press any key to begin."
wait key
cls
sprite 1,500,240,1

`Game loop
do

   `Creating a new alien ship
   if alientime = constant1
      k=spritenum(spriteplace)
      wait key
      sprite k,0,rnd(480),2
      rotate sprite spritenum(spriteplace), 270
      alienships = alienships + 1
      spriteplace = spriteplace + 1
      wait 500
   endif

   wait key

   `Moving all alien ships
   if alienships > 0
      for n = 0 to alienships
         move sprite spritenum(counter), 10
         counter = counter + 1
      next n
   endif

   `Sorting out variables
   counter = 1
   shipx = sprite x(1)
   shipy = sprite y(1)
   if alientime >= constant1 then alientime = 0
   alientime = alientime + 1

   `Shooting
   if spacekey() = 1
      sprite 2,shipx,shipy,3
      rotate sprite 2, 90
      move sprite 2, 15
   endif

loop

wait key
end

[CODE/]

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This is my unfinished game. The problem is, when i go to move all alien ships, and command it to use index 1 in the spritenum array, it tells me that the sprite does not exsist.
Copy it into DBPRO yourself if you want.
Please help!!!

 

[svennnob]

Try putting before EVERY command that has to do with sprites 'if sprite exist(sprnr) = 1' and after it 'endif'.