Question: I just tried running my game on a friend's laptop, but for some reason it crashes. The exported .jar runs fine on my machine, and some others too. I can see that is has something to do with the glDrawArrays function, that is this code:

```
glPushMatrix();

glTranslatef(pos.x*world.chunkSize.x, 0.0f, pos.y*world.chunkSize.z);

glBindBuffer(GL_ARRAY_BUFFER, vao_id);

glVertexAttribPointer(world.game.positionAtt, 3, GL_FLOAT, false, 36, 0);
glVertexAttribPointer(world.game.normalAtt, 3, GL_FLOAT, false, 36, 12);
glVertexAttribPointer(world.game.texCoordAtt, 2, GL_FLOAT, false, 36, 24);
glVertexAttribPointer(world.game.lightAtt, 1, GL_FLOAT, false, 36, 32);

glDrawArrays(GL_TRIANGLES, 0, arraySize / 9);

glBindBuffer(GL_ARRAY_BUFFER, 0);

glPopMatrix();

```

As said, the exact same .jar runs fine on my system, and some more I have tried it on.

My friend's pc has Intel HD Graphics 3000, with GLSL version 1.40 and OpenGL 3.1.0.

Crash dump: <http://pastebin.com/X8x4xX8j>

Thanks in advance.

Answer: 
The function you want is `instance_number(obj)` ([documentation found here](http://docs.yoyogames.com/source/dadiospice/002_reference/objects%20and%20instances/instances/instance%20functions/instance_number.html)). 

> 
> This functions returns the number of instances of a object that exist
>  in the current room.
> 
> 
>
You should use `instance_number(jellyfish)` instead of `instance_count`.
`Instance_count` are ALL objects and `instance_number(obj)` is the count of A SPECIFIED object.