I sent someone a private message... yet total private messages in sent folder = 0. I sent a follow up (did you get the earlier message?) and... total private messages in sent folder = 0. Are my messages getting through at all? What's going on here? (After sending, I did receive a screen that said, in effect, "Your message has been sent.")
You have an option on your profile that determines whether sent PMs are saved. The default setting is to save a copy to Sent Messages. You must have unchecked the box at some point while setting up your profile. There is also a checkbox at the bottom of the New Private Message page that allows you to overrided the default for the current message. The initial state of the checkbox is whatever the option is set to in your profile. If you're not sure if you are successfully sending, you can send a PM to yourself.