Http web server with inactive status in HAproxy [503 Service unavailable]

[wesleylc1]

Hey, guys,
As shown in the image below, my responsive backend on port 80 http returns with the information (503 Service unavailable) and, in the Statistics Report, displays the information (Status Down and LastChk L7STS / 503 in 0ms), please help me resolution.

Thank you in advance!