I'm working on an addon that is supposed to leave a battleground queue for me, but when my addon calls AcceptBattlefieldPort(1, 0) I'm told that the call requires a hardware event. This is contrary to the documentation for this function at http://wowprogramming.com/docs/api/AcceptBattlefieldPort and http://www.wowpedia.org/API_AcceptBattlefieldPort which both state that you should be allowed to leave a battleground queue without an hardware event.
Is this documentation outdated/wrong, or am I using the function wrong somehow?
If it is working as intended, why aren't addons allowed to leave battleground queues? Join I fully understand why shouldn't be allowed, but leave?

Note: You are allowed to leave BG queue with this function if you call it through a macro or run it as a command, calling the function after an event in an addon does not seem to work, though.