Download webpage using powershell

I'm using the following code to try to download a webpage in powershell:

$web = New-Object Net.WebClient
$web.DownloadString("http://fqdn/rs_server.dll")

But it just returns to a PS> prompt.  No errors or anything.  If I enter an invalid address, I get an error.  If I enter another site, such as bing.com, it pulls back the data.  Any thoughts?

When I go to http://fqdn/rs_server.dll in IE, the page displays as expected.