Maximum Landmark Altitude?

I'm having trouble with Landmarks.

I notice a lot of people are running businesses from builds high up in the sky, presumably to reduce lag. I'm curious how they get their landmarks to work, though. If I click on a Landmark that is, say, (xxx, xxx, 4000), it doesn't take me to that altitude. Instead, I arrive hovering just above the land. The location is correct, but the altitude isn't.

I'm wondering, is this a bug with certain sims, or is there a limit on how high a Landmark can send an avatar?

I can't imagine it's a limit, but if it is, how do businesses get their customers up to that altitude? I'd appreciate any advice on this.

MY landmarks at 3950m always work without a problem.

A landmark itself works to 4096 Meters. HOWEVER, there is a bug in event listings and possibly in Classifieds that the altitude is capped at 768 Meters if the landmarked altitude in the ad is above that height.

If you TP to an actial landmark for a high altitude location, and arrive very close to the ground, the merchant almost certainly has a designated landing point set, near the ground, and may not realize that the owner is the only one the LM will work right for! Everyone else will end up at the landing point for the parcel, no matter what LM they use.