My Voting Annoyance

So, my wife and I moved over the summer, and a month or so ago I mailed in our new voting registration forms. A week ago, my wife got her sample ballot and voter pamphlet. I didn't get anything. So today I checked things on the County Registrar-Recorder's website to verify my registration, and it turns out I'm not registered at my new address. I am, however, still registered at my old address (same county), but getting over there on election day would be a pain in the butt. Thankfully, though, I was able to order a vote-by-mail package, and today was the last day to do that. I'm kinda doubtful my vote-by-mail stuff will arrive in time to return it by election day, but we shall see.

Still, though, that was annoying. Why didn't they register me? Did my form just get lost, or did I make some sort of mistake on it? Is it even legal for me to vote at my old address when I don't live there anymore, or is this one of those diabolical voter fraud schemes that Republicans are so worried about?

I'm also, of course, in different local districts, but I'm more familiar with the state assemblyman in my old district (Mike Eng) than the one at my new residence. I'm fairly positive on the congresswoman in my old district (Hilda Solis), but she's literally the only person on the ballot, so there's not much point in voting in that race. The Republicans didn't even field a candidate. My new congressman is Brad Sherman, and there's not any plausible scenario where he loses, despite the presence of two other warm bodies (a Republican and a Libertarian) on the ballot.