Hi, just trying to help..
If you check the spreadsheet, you'll see that for the 51st period, your starting post is 482 and your end post is 490, hence the total post you did for the week is less than 10.. If you refer to the first page, you'll notice that we have to do 10 posts minimum each week.
Hence, the reason why you didn't get your payment is because you didn't meet the minimum post criteria.