Amount Credit Problem

hi everyone
can someone pls tell me why amount credit showing in sales invoice on 28/4/2017as there is no credit left after 17/4/2017 asshowing in transaction screenshot.

You have not provided enough information to answer your question. Although you do not say, it appears the first screen shot may be a drill-down on the Accounts receivable column for a customer in the Customers tab. Is that correct? If yes, is it the same customer to whom the invoice in the second screen shot was sent?

You also say there is no credit left after 17/4/2017. But there is: 72.00. Since you have obscured reference numbers in your first screen shot, it is not possible to track what happened.