The requested instance is either invalid or not running

I try to set up a datasource to SQL server 2008 Express.

And I get always that message :

The requested instance is either invalid or not running.

I spent a full day looking at all forums threads, I have learn a lot,

Looking through all Google return on that subject, but it still not working.

I ask for help to solve this situation.

Here is my situation :

- Windows server 2008 R2 - CF9.0 - SQL server Express 2008

- Working through TSE (terminal server)

- on SQL server , I can acces the management studio, connect, create DB, anything

- I can Stop/Restart the SQL server service throuh the SQLconfig manager

- I have enable TCP/IP in SQLserver for 2 IPs : 127.0.0.1 and the server externel IP on which I connect through TSE, both on port 1433

- SQL server Express 2008 is installed on Hard Disk D:  (not on C:)  (C is small for diskspace)

- The SQL server Instance showed in SQL management Studio is : LARDE\SQLEXPRESS

- Authentification in SQL server : SQL server and Windows

- the CF datasource is declared as follow :

     Driver : Microsoft SQL server

     datasource name : any

     database : the accesible SQL database name where i created a new table

     server : LARDE\SQLEXPRESS   port : 1433

     no login

And I get this error in CF admin datasource : The requested instance is either invalid or not running

- I tried also with a new connection on SQLserver (username/password),
  add it in the datasource declaration (user login)

  same error.

It seems to me that it is a question of Coldfusion access to that instance of SQLserver

I have the same config at home on local, all is working fine. (difference is TSE)

Thanks for any idea,  help.