I've noticed in ArmA (unlike OFP) the UserActions assigned to addons (be it scripted or part of Config) seem to be very difficult to trigger being within the radius and have it appear on your menu.

Armored_Sheep (BIS dev): User action appears if you are within defined range (config, memory points in model) and pointing your cursor on some visible part of the model (View geometry). Usualy ladder objects have problems, because view geometry contains nothing that you can point at.