What is the status of your account? I have not tried that on a toon less than level 40. Would be odd for them to give you a quest you cannot do.
The invisible walls were there early on to keep lowbies from swimming into hostile lands.
If you are on a demo account you may be blocked from SL content. I was able to do this on a "returning" vanilla account prior to adding my SL key, so...
If it helps... the quest is one of the worst ive ever seen, might just skip it :P