I've tried adding Seacor as well. I think he's right; we have to be online at the same time to add each other to friend's lists. Kind of lame, but it's something that can be remedied.
I think you only have to be online together the first time to add people. After that, you will be able to instantly warp to your friends by selecting them from the list, according to a moderator at the Capcom Unity forums.
I'm online for another hour or so, if anyone wants to try adding me to their friends list.
Also, Lindy, I noticed that the server messages state that the Monster Hunter Server maintenance occurs between 12 AM and 4 AM on Tuesdays. It didn't indicate which time zone that might be, so it might be worth noting when scheduling hunting days.