When does the board shift down with hay?

[cad33]

I can't figure out how or when the board shifts down when you destroy hay. I've been playing for a while and right now, I've had the board shift when I've had 4 lvls of hay and not shift when I had fewer.

Right now, from left to right, I have the following hay stacks:

3,2,1,2,1,0,0,1,1

and it won't move. It looks like I have to get below 3, but sometimes I'll end up with as many as 5 or 6 stacks. How can I play the game if I don't know the rules. Any why isn't it a player option to scroll down?

[FrozenTurtle]

There's a couple scenarios which would make the screen scroll down on the hay levels. From the above scenario you presented, it appears that you hadn't quite eliminated enough hay bales on the screen for the level to scroll down. We can't really provide any specifics on these game mechanics, but we encourage you to experiment. You might try eliminating one of the hay bales in the far left column and see what happens.