Can't TP to skybox over friend's land

Sorry if this has been addressed already (I looked but didn't find it).

A friend is letting me place a skybox above their land. I can rez things, move and edit etc, and - with flight feather - can fly as high as I need to go. The problem is that after placing and arranging my skybox, creating a landmark in it, and going somewhere else, I cannot TP back to the skybox. I can fly back there, but cannot just TP. I've tried it at 300m, 400m, and 500m, always with the skybox dead center over the land below and not over lapping any property lines. Like me, my friend is fairly new to SL, and doesn't know how to solve this for me. Unlike me, my friend has no problem TPing to my skybox or anywhere else in, on, or over their land. The land does not currently have any restrictions, security devices, bans, etc. on it. Is there something I or my friend can do to enable me to TP to my skybox? (I don't know whether a possible approach could involve creating a group, but I'm hoping for an answer that won't involve that.)

Thanks in advance for any help!

Do you get some kind of message when you try to tp? What does it say?

Check to make sure there's no "Landing Point" set. See http://wiki.secondlife.com/wiki/About_Land.
(EDIT: ... and that Teleport Routing is set to "Anywhere"

You might have your friend check to see if he set a TP point in the land controls (maybe by mistake)? If a TP point is set, then everyone who TPs into the parcel TPs to that point, regardless of the coordinates of their landmark.

AH!!! Thank you all for your speedy and helpful responses!

Yes, my friend checked and the land was set to let people only teleport in to one location. They changed it to "anywhere" and my next TP attempt worked!

Thanks very MUCH!