Ubuntu Apache加载proxy模块

Apache配置一个反向代理
reload配置后显示报错，配置文件中代理模块未configure。
无法识别参数：
ProxyPass
ProxyPa***everse

查看/var/log/apache/error.log

日志警告：
[warn] proxy: No protocol handler was valid for the URL /. If you are using a DSO version of mod_proxy, make sure the proxy submodules are included in the configuration using LoadModule.

处理方法：
a2enmod proxy proxy_ajp proxy_balancer proxy_connect proxy_ftp proxy_http