There are a couple of reasons this happens, and neither means anything has gone wrong:
You've already earned this month, and you're on Free. Free is a flat 200 points a month however many payments you make. If you pay weekly, those land on the first payment of the month.
You've hit your monthly maximum. Premium members earn up to 2,000 points a month, or 10,000 on welcome rates. Once you're there, further payments that month won't earn.
If you're on Premium and pay weekly, every payment should earn until you reach that maximum. If one hasn't, get in touch.
Tap the points box on your rent and mortgage screen to see what you're earning and when.