As it happens, my LiveJounral account was unvalidated–which is why I wasn’t getting cross-posts to LJ. But I validated my e-mail address, and now all is well.

Edit: I see that the WordPress plugin LJ-crosspost automatically posted all my entries in LJ since I had the original problem. Wow! That’s pretty slick!

…so I just deactivated my Livejournal cross-posting WordPress plug-in, put my credentials back in, and reactivated it. Let’s see if it works onw.