Just tested that for you on the other thread and it seems to work OK for me.When trying to quote this post (#366 in the Trespass incident at Manchester Piccadilly (11/03) thread) I get an error saying that I must enter a message with more than 5 characters, despite having written a couple of paragraphs in response which posted fine when I removed the quote.
This happens when you haven’t closed the quote properly. Make sure it’s closed, then try again. If you don’t close the quote the forum doesn’t recognise you’ve typed anything.