RPC over http connection exchange 2010 and outlook2010

Hi there,
May be this would help me to identify problem:  My OWA is fine and clients work fine. via http://mail3.mydomain.com.

''the action cannot be completed.  The connection to Microsoft Exchange is unavailable.  Outlook must be online or connected to complete this action.''
This error pops up everytime I try to connect to my Exchagne 2010 RPC over https with outlook 2010

I am using external address https://mail3.mydomain.com
internal address of server exchage2010: https://exchange2010.mydomain.com
also: https://autodiscover.mydomain.com

All top three addresses are inclusive in my SSL certificate:


Outlook 2010: settings:
under connections tab:
connection settings: https://mail3.mydomain.com   (my external OWA address)
connect using SSL only checked
Only connect to proxy servers that have this principal name...........
msstd://exchange2010.fernhillschool.com  (my internal exchange server name, note that my ssl certificate has this name)
On slow networks, connect using http..............checked
NTLM auth under Proxy auth settings is selected



On my Exchange 2010:
Under EMC:
server config, CAS:

Under Client Access, right click over server name: outlook anywhere External host name: exchange2010.mydomain.com and NTLM auth is selected

Under outlook web app
Internal URL https://mail3.mydomain.com/owa
External URL https://mail3.mydomain.com/owa
under authentication tab, USE forms based auth, UPN selected

Under ecp:
internal URL: https://mail3.mydomain.com/ecp
External: https://mail3.mydomain.com/ecp
authentication=forms based authentication

Exchange active sync:
internal url: https://exchange2010.mydomain.com/Microsoft-Server-ActiveSync
External url: https://mail3.mydomain.com/Microsoft-Server-ActiveSync
authentication tab: Basic auth checked, ignore client cert

OAB:
inteternal URL: http://exchange2010.mydomain.com/OAB  <<<......note that this is http
External URL: https://mail3.mydomain.com/OAB


Under POP3 and IMAP4:
POP3: under authentication, x509 cert: mail3.mydomain.com
IMAP4: under authentication, x509 cert: mail3.mydomain.com


I need help plz

as I said previously in my comment

your exchange server is set for BASIC authentication

Exchange active sync:
internal url: https://exchange2010.mydomain.com/Microsoft-Server-ActiveSync
External url: https://mail3.mydomain.com/Microsoft-Server-ActiveSync
authentication tab: Basic auth checked, ignore client cert

so:-
in your HTTP Proxy settings, change NTLM authentication to BASIC.

then login using your correct username notation and password.

Hi scobber,
I have confirmed that I checked the Basic auth in outlook 2010, when I click check names it keeps on poping up username and pass window, I click ok ok, then sometimes the error becomes the same as my last post.
A new error in outlook 2010, 'the name cannot be resolved the connection to mic exchange is unavailable.  Outlook must be online or connected to ..............................
Help plz

Is it normal.  On my exchage 2010 under iis when I click to browse the default website *80(http) it gives 403.4 forbidden the page you are trying to access is secured with ssl....
where as browse 443 is fine

OK finally I got connected:
In outlook 2010
Under the server: it should be the name of the local server
username: only username
Under connection via http:
https://mail3.mydomain.com
msstd://mail3.mydomain.com
select both options of http
Basic auth

Thank all I really appreciate your time.