w00dm4n posted...you can only streetpass once a day.
did you set up the old 3ds with the same account? i don't think it'll let you streetpass yourself
Actually, you can Streetpass with another 3DS approximately every 8 hours.
TC, I've had this happen a couple of times, once after a system transfer to an XL and another time a few weeks ago after having the battery out of the system. The good news is that both times, Streetpass starting working again. The bad news is that there's really no way to tell how long that might take. It took a couple of days after the transfer, but took 5 days after having the battery out.
Try changing your default Mii to another one you create and turn off Streetpass for a full 24 hours. Then, reenable it and switch back to your regular Mii. That's Nintendo's official line on it and it may or may not help, but it's worth a shot. I always read that you might have to pass someone you never passed before to get it going, but the last time it happened, I ended up passing someone I had already passed once before and then it started passing my other 3DS the next day.