error code -400 using URI with CGI-params ??

Hi all,

if I try to send a GET request with parameter (like
'http://www.bernhardtsweb.de?session=4711") over a proxy, I always get the
error number -400 in my own code sample and also in the LibWWW sample
'WinCom'!
The same request, sent directly without using proxy settings, the sample
operates perfect!

Does anyone have an idea, why a primitive HTTP request fails with an unknown
error (-400) by passing this request through a proxy?

Thanks for any answers!

Juergen