我怎样才能让Pinax的OpenID与NAT协同工作?

我在NAT后部署了一个Pinax gunicorn部署,向外的Apache服务器向gunicorn服务器做ReverseProxy。 总的来说,它运作良好,但是当我尝试使用OpenIDlogin时,出现错误:

Proxy Error The proxy server received an invalid response from an upstream server. The proxy server could not handle the request POST /openid/register/. Reason: Error reading from remote server 

我怎样才能让Pinax与NAT合作?