Have absolutely no time to understand internals of the problem achieved: what means MS Internet Transfer Control error "Client authorization not setup" and what should I do to prevent it?
Portions of the code:
itcS1.URL = "https://a.b.c/d/
itcS1.UserName = "crin"
itcS1.Password = "password"
On control's StateChanged event it reports state 11 - Error and incS1.ResponseInfo contain shown error.
Using http protocol everything works pretty well and on state 12 (response completed) returns correct data.
ALL data is valid, server is ok and everything works perfect using IE.