https://bitcointalk.org/index.php?topic=2766177.0More info in the meta thread
Why is my activity stuck/not moving?Because you can only get 14 activity every two week period. You will have to wait until the next period starts to get another 14.
Why has my rank/activity not updated?It can take up to an hour to update. Just be patient.
Can I get more than 14 activity in two week period?No. However, you can technically get more than 14 activity in a fortnight if you sign up in between periods, but you can't get more than 14 activity in a fortnightly period. For instance, if the period starts on a Wednesday and you sign up on Tuesday you can get 14 points on Tuesday and another 14 on Wednesday providing the period has started. You will then have 28 activity points but won't be able to get any more until two weeks' time when the new period starts.