Install and configure Haproxy failed for wrong reason

For the install and configure haproxy task ,it failed stating haproxy is not able to connect to App Server 1 on port 6400 .But the config error was with App server 3 ,ie , the mistake was in the last as shown below

    server stapp01 172.16.238.10:6400 check 
    server stapp02 172.16.238.11:6400 check 
    server stapp02 172.16.238.12:6400 check

I just want to know if the mistake that i did was the actual cause or something else to learn from my mistakes