Client Access server %1 tried to proxy Outlook Web App traffic to Client Access server %2. This failed because one of these ...

Client Access server %1 tried to proxy Outlook Web App traffic to Client Access server %2. This failed because one of these configuration problems was encountered:
1. %3 has been set to use "http://" (not using SSL) instead of "https://" (using SSL). You can modify this by setting the internalNLBBypassUrl parameter of the Exchange Web Services virtual directory this proxy traffic is going to. You can set that parameter using the Set-Webservicesvirtualdirectory cmdlet.
2. The destination virtual directory returned an HTTP 403 error code. This usually means it's not configured to accept SSL access. You can change this configuration by using IIS Manager on the Client Access server %4.
If you don't want this proxy connection to use SSL, you need to set the registry key "AllowProxyingWithoutSSL" on this Client Access server and set the internalNLBBypassUrl and SSL settings for the Exchange Web Services virtual directory this proxy traffic is going to accordingly.