Problem with ProxyPass if url part end with .dll

[hdenys]

Hi -

I am trying to use Proxy Module to make a proxy like this:
ProxyPass /foo <destination_url>. If destination part is a web page like http://foo.example.com/bar or http://foo.example.com/index.html, it works perfectly. But in case if destination part is something like http://foo.example.com/bar.dll I get a page with the message "The specified module could not be found."

bar.dll at the end of the url references to the application which runs under IIS. If I type this url (http://foo.example.com/bar.dll) in my browser - it is working.

It seems that the issue is this dll file. Is it any issue with access to it? Does anybody can give me any ideas what is causing the issue?

Thanks,
Denys