i was reading some tuts and they said something along the lines of "if the func_usableladder is inside any brush or entity, the ladder may not work". the truth is, however, the entity cannot even TOUCH anything AT ALL . if it does, the ladder and whatever its touchin will interfere with eachother and your camera will do a little shaky thing when you are trying to use the ladder....showing that it is struggling to get you up or down that ladder. just take note that the func_usableladder cannot touch anything if you want it to work.