[horde] Problems connecting to MS-SQL

[Jim (Work)]

Doing a new install of Horde and having problems with the database
connectivity. 

Running 
 - IIS 6 
 - PHP 5.2.3 
 - msmsql module for PHP shows in the PHP info page 
 - Horde Groupware Webmail Edition 1.2.2 

MS-SQL server instance is running (has other databses so we know it's OK). 

Server and login details set up correctly in config.php, as shown below.
DB login is sa so there should not be any user issues.

$conf['sql']['persistent'] = false;
$conf['sql']['hostspec'] = 'DSVR007108\RAYNET';
$conf['sql']['username'] = 'sa';
$conf['sql']['password'] = '*******';
$conf['sql']['port'] = 1433;
$conf['sql']['database'] = 'horde';
$conf['sql']['charset'] = 'utf-8';
$conf['sql']['phptype'] = 'mssql'; 

When taking option 2 from the setup prorgam, I get this:
Loading database module...
Creating database...
[ ERROR! ] Creating the tables failed. Please see the manual at
docs/INSTALL for how to setup the database manually.
Error messages:
MDB2 Error: connect failed
connect: [Error message: unable to establish a connection]


Anyone any ideas why?


Thanks.


 
Jim