Conversations (aka PMs) are only available to Senior Members
or above, so if you're trying to send one to a lower UserGroup you won't be able to... also due to the influx of PMs I've received in recent weeks only the Staff can send them to me now.
Regarding replies, that is correct if you click the Reply
button link.. to quote someone you would have to click the Quote
button link and then 'Insert Quotes' once it brings you to the bottom.
However, it's recommended
to use the @ symbol
next to the user's name instead to mention them in posts here as quotes are generally stripped in database backups to save space.