Compare to Current Version doesn't work - results in IIS config error

SLACRay

We are running TeamSite 7.2.1 on a Windows 2008 server, with IIS running as the web server for previewing of files (the website we're managing in TeamSite is a .NET app). We have the Compare Differences feature working successfully (comparing WORKAREA/sharing to STAGING), as well as regular file previewing in WORKAREA/shared and STAGING.

However, when reviewing the Versions of a file in WORKAREA/shared, and then selecting 'Compare to Current Version' for a previous version, it results in a 'Server Error in '/' Application' error.

I suspect we're missing some proxying settings in iw.cfg, as well as maybe some additional web application setup in IIS to map the proxy settings to.

I can provide any additional info you might need, if you think you can help me.

Much thanks!