add a network place (with wizzard)

hi,

I can't to realize this thing.
I've a valid URL, like "http://mywebserver.com/share/"
and it works fine with IE (anonymous login, no password)
When I'm trying with the add network place wizzard, I put this URL,
and it appears an dialogbox for "connect to".
Normaly on the IIS WEB server which have this share onto, the
anonymous log is : iusr_myserver, and have no password.
If I put this log, I can't log.

Is it normal to have this dialogbox for authentication.
And how to resolve this problem ?

A great thanks for all !