If you are knocked back into blocking terrain, or a wall, or the edge of the map, or off of elevated terrain, you take knock back damage. Off of elevated terrain you take 2 damage instead of 1 as well.

You can not be knocked back up a ladder. You will be stopped by the border of elevated terrain and be dealt 1 knock back damage.

I think he's talking in general about a transition point (ladders as opposed to stairs don't really exist anymore.)

Doesn't really matter. Knock back can't go past a square of higher elevation, even if it is a stair or ladder. RB, page 11:

KNOCK BACK DAMAGE
A character’s knock back path can’t continue
beyond a square that blocks movement, elevated
terrain of a higher elevation or the edge of the
map. If it would do so, the character’s knock back
path ends in the square before its path would
cross into any of these areas, and the character
is dealt 1 damage, as shown in Figure 10. This
damage dealt is called knock back damage. It can
be reduced as normal and is applied separately
and after damage dealt by the attacker. Knock
back into a terrain feature does not destroy it.

Ok im glad to hear that. i also thought i had to be on the squares that have the arrows and level number (transition point). sorry about saying ladder prob made a ez question harder. but anyway thanx for the feedback