I just posted a question on PSE, and it got 2 upvotes. So, I get 20 + 1 existing rep. So, naturally, I have enough to talk in chat. But, when I opened The Sphinx's Lair, it says I don't have enough! Is this a glitch, or do I have to do something first?
Chat profiles aren't synced immediately with your network account; it automatically refreshes every couple hours or so (or when a moderator force-refreshes your chat profile). Especially for the initial 20 reputation to allow you to chat, it's going to take a bit of time for chat to catch up to the main site.