Web Performance testing using VS2010 "Testing a file download"

I am trying out the VS 2010 testing tools for the first time. And I tried recording a web performance test and my actions had a file download implemented as in the KB article here http://support.microsoft.com/kb/812406 by streaming chunks of 10000 bytes.

However my test is failing at the download saying "The response stream has been closed".

Please help me understand why it is happening this way also any suggestions how you would test such a file download.

开发者_如何学CMy main aim was to see how the download was performing for a load test with Intercontinental 350kbps connection on files of about 30-50 MB.

Thanks.