Apache error during testing using apache2.2.4 as load balancer

Below is my httpd.conf

  Listen 8082
   <VirtualHost *:8082>
    ServerName ampsit.midea.com
    ServerAlias ampsit.midea.com
    ProxyPreserveHost On
    ProxyRequests Off

   <Proxy balancer://mframework/>
        BalancerMember http://devcloudsit.midea.com:61000 loadfactor=1
    </Proxy>
    ProxyPass /mframework/ balancer://mframework/mframework/ timeout=5 maxattempts=2
    ProxyPassReverse /mframework balancer://mframework/mframework/

   <Proxy balancer://amp/>
        BalancerMember http://10.17.158.135:61001 loadfactor=1
        BalancerMember http://10.17.158.136:61001 loadfactor=1
    </Proxy>
    ProxyPass /amp/ balancer://amp/amp/ timeout=5 maxattempts=2
    ProxyPassReverse /amp balancer://amp/amp/
</VirtualHost>

Error message

[Thu Aug 09 18:46:34 2018] [error] [client 10.17.158.142] (70007)The timeout specified has expired: proxy: error reading status line from remote server 10.17.158.136:61001, referer: http://ampsit.midea.com:8082/erpamp.html [Thu Aug 09 18:46:34 2018] [error] [client 10.17.158.142] proxy: Error reading from remote server returned by /amp/pointinfo/ampBasePointInfo/getAmpCurrentCheck, referer: http://ampsit.midea.com:8082/erpamp.html [Thu Aug 09 19:00:38 2018] [error] (111)Connection refused: proxy: HTTP: attempt to connect to 10.17.158.136:61001 (10.17.158.136) failed [Thu Aug 09 19:00:38 2018] [error] ap_proxy_connect_backend disabling worker for (10.17.158.136) [Thu Aug 09 19:01:18 2018] [error] (111)Connection refused: proxy: HTTP: attempt to connect to 10.17.158.135:61001 (10.17.158.135) failed

PS:

   10.17.158.142 is nginx ip
    10.17.158.135、10.17.158.136 is apps ip   
    yesterday 6:30 PM happened, but today 7:00 is ok！Nothing changed！ amazing！