IIS 6 bad request (invalid verb)

this is a request that i am trying to send to an .aspx page on the IIS
6 server, using an c++ application.

POST /demo/kllsues/vtr/test.aspx
Content-Type: application/x-www-form-urlencoded
Content-Length: 242766

userna.......

but i get an

HTTP/1.1 400 Bad Request
Content-Type: text/html
Date: Wed, 21 May 2003 14:17:52 GMT
Connection: close
Content-Length: 35

<h1>Bad Request (Invalid Verb)</h1>

reply, and this perfectly works on iis 5 on xp, what might be wrong
here, any ideas ?